System for making dried singulated crosslinked cellulose pulp fibers

ABSTRACT

This invention provides a dried singulated crosslinked cellulose pulp fiber product as well as an apparatus and a method for forming singulated, crosslinked, and dried fibers. In accordance with the process, a feed pulp containing a crosslinker is delivered to a jet drier. The jet drier singulates and dries the feed pulp. The singulated and dried fibers are collected from the jet drier. The feed pulp may be further treated with a treatment substance. The jet drier may be maintained at negative pressure. The product fibers may have low knot count, a low fines count, as well improved kink, curl, and twist. The apparatus for carrying out the process may include a pretreatment station for supplying the treatment substance, a pulp feed device designed for pulp, a pulp feed device designed for pulp and foam suspensions, and/or a fiber separation station having a vacuum conveyor.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a divisional of application Ser. No. 10/051,392,filed Jan. 16, 2002, which is a continuation-in-part of application Ser.No. 09/998,143, filed Oct. 30, 2001, priority from the filing dates ofwhich is hereby claimed under 35 U.S.C. § 120.

FIELD OF THE INVENTION

The present invention relates to a system for making a dried singulatedcrosslinked cellulose pulp fiber product using a jet drier.

BACKGROUND OF THE INVENTION

Dried singulated cellulose pulp fibers are desirable for many productsfrom absorbent personal articles to a reinforcer in concrete. Currently,in the most common process of making singulated fibers, a roll ofconventional pulp fibers is hammermilled into singulated fibers. Thisprocess is energy and time intensive, requiring many steps and pieces ofprocessing equipment. Each piece of processing equipment requires asignificant capital expenditure and occupies valuable factory floorspace. Further, the current hammermilling process often produces fiberswith undesirable physical properties such as low kink, curl, and twist.

This dry singulated pulp will also contain knots of fiber, sometimesreferred to as nits or nodules. Knots are fiber clumps that remainstrongly adhered to one another as can be seen by placing a smallportion of pulp into a clear beaker of water and stirring the water tomix the fibers. Most of the fiber will mix into the water as singularfibers; however, there will be fiber clumps that are readily visible.The fiber clumps, or knots, are undesirable by-products of thehammermilling process. The amount of knots in a pulp that has beenhammermilled can be quantified by using a screening system withacoustical energy used as the means to classify the fiber into amountsof knots, accepts, and fines. It is desirable to have low knots andfines and high accepts where the accepts are the singulated fibers.

Canadian Patent No. 993,618 (Estes, 1976) describes a process forproducing a low density fluff pad or batt from individual fibers thathave significant kink and interlocking to provide improved batt strengthand higher bulk. In accordance with the process, wet pulp is separatedinto individual fibers during the drying stage. The process uses fluidjet drying equipment that employs air-jets or steam-jets for separatingthe. fibers. The fibers are laid on a perforated screen upon exitingfrom the jet drier. The process of the Canadian patent produces a mat ofinterlocked fibers.

Crosslinked fibers are conventionally produced by wetting an alreadydried roll of conventional pulp fibers with a solution containing acrosslinker prior to hammermilling. The hammermilled pulp containing acrosslinker is then run through a flash drier and further heated in anoven to complete the crosslinking process. This crosslinked pulp has aknot content that is greater than 15%. It is desirable to have a loweramount of knots in crosslinked pulp. Also, this conventional process isenergy intensive, and therefore expensive, because the pulp is driedbefore it is rolled then hammermilled in wet form with crosslinker thendried again.

Flash drier systems have been used to directly dry dewatered never-driedpulp. The use of flash driers to directly dry dewatered never-driedpulp, however, produces a dried pulp with a high amount of knots.Typical knot amounts for flash drying of never-dried pulps are 30%-40%.Crosslinker containing pulp dried in this manner also results in a knotcontent similar to or exceeding this level. An overview of a commercialflash drier, the Flakt Flash Drier, and typical flash drier equipmentinstallation is provided by Larsson and Lindstrom, 1996 (“RecentDevelopments in Pulp Drying”, Larson, O., and B. Lindstrom, The World ofPulp and Paper Week 5^(th) International Conference on New AvailableTechniques, Jun. 4-7, 1996, Stockholm, Sweden).

SUMMARY OF THE INVENTION

This invention provides a dried singulated crosslinked cellulose pulpfiber product as well as an apparatus and a method for formingsingulated, crosslinked, and dried fibers that have a relatively lowknot content. In accordance with the process, wet pulp containing acrosslinker and air are introduced into a jet drier. The pulp is driedin the jet drier to form singulated pulp fibers. The pulp is removedfrom the jet drier and separated from the air. The process may be usedon several types of feed pulp and on further treated feed pulp. Theproduct formed by the process has advantageous properties such as a lowknot count, a low fines count, as well as improved kink, curl, andtwist. The apparatus for carrying out the process may include apretreatment station for supplying a treatment substance, a pulp feeddevice designed only for pulp, a pulp feed device designed forsuspensions of pulp in foam, and/or a fiber separation station having avacuum conveyor.

In accordance with the process described above, the wet pulp containinga crosslinker treatment substance may be further treated with atreatment substance before drying to reduce the knot content of the pulpfibers. The process also includes producing singulated pulp fibers byintroducing wet pulp and air into a jet drier through a rotary airlock.The rotary airlock has vanes and a housing with the end of the vanesbeing spaced from the housing by a distance sufficient to prevent wetfibers from clogging the airlock. The process includes producingsingulated pulp fibers by withdrawing the fibers from said jet drier inan air stream at a velocity sufficient to prevent the fibers frominterlocking and knotting. The process also includes producingsingulated pulp fibers by withdrawing the pulp fibers from an outletfrom said jet drier under a partial vacuum.

The pulp product includes singulated, crosslinked, and jet dried fiberswith a knot count equal to or less than preferably 15%, more preferably10%, even more preferably 5%, and most preferably 2%. The product may befurther treated with a treatment substance selected from the groupconsisting of a surfactant and a mineral particulate. The product ofsingulated, crosslinked, and jet dried fibers can be incorporated intoconcrete, an absorbent article, a plastic product, a paper product, or afilter product.

The drying system for the processing of pulp into singulated,crosslinked, and dried fibers includes a jet drier, a pulp supplystation, an air supply station, an outlet flow conduit, and a fiberseparation station. The jet drier has a jet conduit, a manifold for airintake into the jet conduit, a pulp intake for delivery of pulp into thejet conduit, and a fiber outlet for removal of singulated and driedfibers, outlet air and fines from the jet conduit. The pulp supplystation is coupled to the pulp intake for supplying a feed pulp to thepulp intake. The pulp supply station includes a treatment supply sourcefor delivering a treatment substance to the pulp. The air supply stationis coupled to the manifold for delivering air to the manifold. Theoutlet flow conduit is coupled to the fiber outlet for the transport ofthe fibers, outlet air, and fines from the jet conduit. The fiberseparation station is coupled to the outlet flow conduit for separatingthe fibers from the outlet air.

The present invention thus provides a dried singulated crosslinkedcellulose pulp fiber product as well as an apparatus and a method thatenable forming singulated, crosslinked, and dried fibers. The processmay take wet pulp directly from a pulp mill and produce a singulatedproduct from the never-dried pulp by using a drying process thatsingulates the pulp directly. This process forms singulated crosslinkedfibers with greater kink, curl, and individual twist than hammermilledfibers. A further advantage is the ability of the present invention toproduce crosslinked fibers having a low fiber interlock, knot, and finescontent. Other advantages are the further treatments in addition tocrosslinking that can be performed on the pulp that are difficult orimpossible to perform on a roll of dried pulp. Treatments can be done onthe never-dried pulp that reduce the amount of knots, increaseproduction rate, and/or form fibers having desirable characteristics.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing aspects and many of the attendant advantages of thisinvention will become more readily appreciated as the same become betterunderstood by reference to the following detailed description, whentaken in conjunction with the accompanying drawings, wherein:

FIG. 1 is a schematic diagram of a drying system constructed inaccordance with the present invention suitable for carrying out theprocess in the present invention;

FIG. 2 is a schematic view of the drying system of the present inventionwith a cross section view of a jet drier and a fiber separation station;

FIG. 3 is a cross section view of a pulp feed device of the presentinvention;

FIG. 4 is an enlarged cross section view of the pulp feed device rotorof the present invention;

FIG. 5 is a side view of a mechanical mixer and the jet drier of thedrying system of the present invention;

FIG. 6 is an exploded view of the mechanical mixer of the presentinvention;

FIG. 7 is a perspective view of a fiber separation station of thepresent invention;

FIG. 8 is a bottom perspective view of the fiber separation station ofthe present invention;

FIG. 9 is an enlarged perspective view of the fiber separation stationof the present invention;

FIG. 10 is a schematic diagram of an absorbent article of the presentinvention;

FIG. 11 is a schematic diagram of a concrete or plastic product of thepresent invention;

FIG. 12 is a schematic diagram of a paper or filter product of thepresent invention;

FIG. 13 is a schematic diagram of the drying system of the presentinvention including a curing station; and

FIG. 14 is a schematic diagram of the drying system of the presentinvention including a curing oven.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention provides for processes and apparatus for thedrying, treatment, and singulation of pulp into individual fibers withlow interlocked fibers, knots, or nodules. As used herein, the term“dried” in regards to fibers is a term of art generally indicating aweight percentage of water between 2% and 10%, but may fall above orbelow this range. As used herein, the term “air” is not limited to pureair but may include any gas consistent with the present invention. Asused herein, the term “consistency” means the percentage of solidscontent of a liquid and solid mixture. The specific examples set forthbelow are directed to the drying, treatment, and singulation ofcellulose pulp fibers. However, it should be understood that the presentinvention is also suitable for use in processing other types of naturalfibers and/or synthetic fibers.

The present invention comprises a drying system having a jet drierdesigned to dry wet pulp directly from a pulp mill to a singulated fiberproduct. Referring to FIG. 1, a drying system 10 constructed inaccordance with the present invention includes a jet drier 20, a pulpsupply station 40, an air supply station 90, a fiber separation station100, and a fiber collection station 160.

The pulp supply station 40 is coupled in flow communication with the jetdrier 20. The pulp supply station 40 receives supply pulp from a pulpsupply source 42 and provides a feed pulp to the jet drier 20 via a pulpfeed conduit 44. The air supply station 90 is coupled in flowcommunication with the jet drier 20. The air supply station 90 receivessupply air from an air supply source 92 and provides feed air via an airfeed conduit 94 to the jet drier 20. The jet drier 20 is coupled in flowcommunication with the fiber separation station 100 via outlet flowconduit 30. The jet drier 20 exhausts outlet air, substantially driedand singulated fibers, and fines to the fiber separation station 100 viaoutlet flow conduit 30. The fiber separation station 100 is coupled inflow communication with the fiber collection station 160. The fiberseparation station 100 separates the outlet air from the fibers, and mayalso separate a portion of the fines from the fibers. The fibers fromthe fiber separation station 100 are delivered to the fiber collectionstation 160.

In a preferred embodiment, the apparatus also includes a fines removalstation 170 and a noise reduction station 180. The fiber separationstation 100 is coupled in flow communication with the fines removalstation 170 through fines conduit 172. The fiber separation station 100provides outlet air and fines to the fines removal station 170 via finesconduit 172. The fines removal station 170 removes the fines from theoutlet air and recycles the outlet air back to the air supply station 90via air conduit 182. The noise reduction station 180 is preferablyinterposed in air conduit 182 to reduce the noise produced by the dryingsystem 10.

Referring to FIG. 2, the jet drier 20 includes a loop conduit 22, a pulpintake 24, a manifold 26, and a fiber outlet 28. It will be understoodthat, as used herein, the term “jet drier” means any device whichaccelerates air into the loop conduit 22, enabling the simultaneousdrying and singulation of a substance flowing though the conduit 22. Thepulp intake 24 is coupled to the conduit 22 for delivering feed pulp tothe conduit 22. The manifold 26 is coupled to the jet drier conduit 22to deliver feed air via air feed conduit 94 into the conduit 22 througha series of nozzles which are directed to induce a flow within theconduit 22. The fiber outlet 28 is coupled to the conduit 22 to supplyan outlet for outlet air, fibers, and fines flow out of conduit 22.

The conduit 22 is preferably arranged in a closed loop. The conduit 22loop can take various shapes such as circular, elongated rectangular, a“D” shape, square, or other similar shape. Without being bound bytheory, it is believed that when wet fibers enter the conduit 22 loop, acentrifugal separation takes place so that wetter/denser fibers arerecirculated along the outer edge of the loop while drier/less-densefibers move towards the inner part of the loop. Air and dried productexit from a fiber outlet 28 placed along the inner part of the loop. Onesuitable jet drier 20 for use in the present invention is a Fluid EnergyAljet Model 4 Thermajet X0870L manufactured by Fluid Energy Processing &Equipment Company. Alternatively, the jet drier conduit 22 may be in ashape other than a closed loop. For example, the conduit 22 could bestraight. In this embodiment, the fibers may be recovered at the end ofthe conduit 22.

The drying system 20 further includes an outlet flow conduit 30 coupledto the jet drier 20 fiber outlet 28 and associated with the fiberseparating station 100. The outlet flow conduit 30 delivers outlet air,fibers, and fines flow to the fiber separating station 100. The outletflow conduit may include a first material handling fan 32. The firstmaterial handling fan 32 prevents the fibers and fines from settling outof the outlet air if the outlet air slows in the conduit 30. However,the first material handling fan 32 may not be necessary if the velocityof the outlet air maintains the fibers in suspension. The diameter ofthe outlet flow conduit will affect the velocity of the outlet air. Itis desirable to prevent the fibers from settling out of the outlet air.If fibers settle out of the outlet air, the fibers have an increasedtendency to knot or interlock.

The pulp supply station 40 may include a first dewatering device 46. Thefirst dewatering device 46 is connected in flow communication with pulpsupply 42 and pulp feed conduit 44. The pulp supply source 42 deliverssupply pulp directly from the fiberline of a pulp mill to the firstdewatering device 46. The first dewatering device 46 partially dewatersthe supply pulp from pulp supply 42 and delivers feed pulp via pulp feedconduit 44 to jet drier 20. The first dewatering device 46 includes, butis not limited to, devices such as a screw press, belt press, continuouscentrifuge, batch centrifuge, double roll press, or other similardevice.

The supply pulp from pulp supply source 42 will typically have a highfluid content, having a 0.01%-10% consistency, and more typically a3%-10% consistency, although consistencies up to 12% to 15% may beemployed. The supply pulp may be bleached pulp, unbleached pulp,mechanical pulp, chemical pulp, a dissolving grade pulp, once dried andreslurried pulp, or any other suitable pulp. In the present invention,much of this fluid may be removed by the first dewatering device 46.Typically, the first dewatering device 46 removes a portion of the fluidfrom the supply pulp and increases the consistency of the feed pulp to10%-55% prior to drying the feed pulp by the jet drier 20. Preferably,the consistency of the feed pulp is 30% to 50%. The partially dewateredfeed pulp is transported to the jet drier 20 via pulp feed conduit 44.

The supply pulp may be a pressed wet web of pulp having a basis weightof a substantial amount to provide sufficient stiffness to feed the webinto a shredding device. The basis weight may typically be from 500 gsmto 1500 gsm. The wet web supply pulp may be fed into a shredding devicesuch as a rapidly rotating set of rolls containing protruding pins thattear the web into small pieces of pulp, a material handling fan, orother similar device.

The pulp feed conduit 44 may be a pipe, hopper, or other conveyancedevice. Additionally, the first dewatering device 46 itself may serve asa conveyance device. For example, the first dewatering device 46 may bea screw press which could be used to simultaneously dewater andtransport the feed pulp to the jet drier 20. One suitable pulp supplystation 40 pulp feed conduit 44 for use in the present invention is ashaftless screw conveyor designed and manufactured by Martin Sprocketand Gear, Inc., Martin Conveyor Division. The shaftless screw conveyorhas a shaftless screw which feeds wet pulp at an incline that rises uptoward the pulp intake 24 of the jet drier 20. The shaftless screwconveyor has a hopper at the lower end of the conveyor for placingsupply pulp.

The pulp supply station 40 may include a treatment supply source 48 forincorporating a treatment substance into the feed pulp. The treatmentsupply source 48 may be coupled in flow communication to the pulp supplysource 42, the pulp feed conduit 44, the first dewatering station 46, oranywhere along the pulp supply station 40.

The treatment supply source 48 may deliver the treatment substance withany apparatus known in the art. For instance, treatment supply source 48may deliver the treatment substance with a conduit, spray system, mixingdevice, or other device or combination of devices. Where the supply pulpis a pressed wet web of pulp, the treatment substance may be applied tothe supply pulp by a spray system, roller coating system, or acombination of spray system and roller coating system.

Many treatment substances that may be applied to the feed pulp prior tobeing dried and singulated by the jet drier 20 are incapable of beingincorporated into the traditional process of producing dried singulatedfibers. The traditional process is limited in its ability to treat thefibers since they are in a web form. In this web form, treatment of thefibers must be done by running the web through a bath or spraying theweb. The present invention is not limited in this way since treatmentsubstances may be directly delivered to the pulp. For example, thefibers of the supply pulp in the present invention may be suspendedwithin a foam prior to drying by the jet drier 20 or viscous solutionsmay be mixed with the supply pulp. Neither one of these treatmentchoices would be practical with the traditional bath treatment step. Theapplication of treatment substances that are viscous solutions cannot beaccomplished with a traditional pulp machine. Additionally, the harshconditions of hammermilling limit the practicality of the fibersretaining certain compounds that may be used as treatment substances.For example, coating the fibers with mineral particulate such as clay,would result in low clay retention with hammermilling, but in thepresent invention, retention may be significantly higher due to thesingulation being accomplished by air rather than mechanical means.Further, the amount of surfactant used to treat pulp on a traditionalpulp machine is limited due to the adverse effect on operations;however, there is no such limitation with the present invention. Intraditional pulp machines, the surfactant decreases the strength of thepulp web. If enough strength is lost, the pulp web will break undernormal tension encountered on a traditional pulp machine.

The treatment substance delivered by treatment supply source 48 mayinclude, but is not limited to, surfactants, crosslinkers, hydrophobicmaterials, mineral particulates, superplasticizer, water reducingagents, foams, other materials for specific end-use fiber properties,and combinations of treatment substances. The term “surfactant”includes, but is not limited to, oil in water emulsions; surfactantsdisclosed in U.S. application Ser. No. 08/509,401, to Graef et al.; U.S.Pat. No. 3,554,863, to Hervey et al.; U.S. Pat. No. 6,074,524, to Wu etal.; U.S. Pat. No. 6,159,335, to Owens et al.; and Canadian Patent No.947915, to Angel et al., all of which are expressly incorporated hereinby reference. Surfactants impart desirable properties to pulp fiberssuch as reducing fiber to fiber bonding, improving absorbency, orreducing friction of finished webs. Surfactants are used in tissue andtowel manufacturing, and are used extensively in the textile industryfor numerous enhancements. The classes of surfactants include anionic,cationic, nonionic, or ampholytic/zwitterionic surface active materials.Examples of anionic surfactants include sodium stearate, sodium oleate,sodium dodecyl sulfate, sodium dodecyl benzene sulfonate, polyethersulfate, phosphate, polyether ester, and sulfosuccinate. Examples ofcationic surfactants include dodecylamine hydrochloride,hexadecyltrimethyl ammonium bromide, cetyltrimethyl-ammonium bromide,and cetylpyridinium bromide. One class of surfactant is cationicsurfactants based on quaternary ammonium compounds containing fatty typegroups. Examples of non-ionic surfactants include polyethylene oxides,sorbitan esters, polyoxyethylene sorbitan esters, and alkylarylpolyether alcohols. An example of ampholytic or zwitterionic surfactantis dodecyl betaine. Examples of commercial surfactant are EKA ChemicalsInc. Berolcell 587K, which is a cationic surface active agent, andProcess Chemicals, LLC, Softener CWW, which is a cationic surfactantused as a yarn lubricant.

The term “crosslinker” includes, but is not limited to, any one of anumber of crosslinking agents and crosslinking catalysts. The followingis a representative list of useful crosslinking agents and catalysts.Each of the patents noted below is expressly incorporated herein byreference in its entirety.

Suitable urea-based crosslinking agents include substituted ureas suchas methylolated ureas, methylolated cyclic ureas, methylolated loweralkyl cyclic ureas, methylolated dihydroxy cyclic ureas, dihydroxycyclic ureas, and lower alkyl substituted cyclic ureas. Specificurea-based crosslinking agents include dimethyldihydroxy urea (DMDHU,1,3-dimethyl-4,5-dihydroxy-2-imidazolidinone),dimethyloldihydroxy-ethylene urea (DMDHEU,1,3-dihydroxymethyl-4,5-dihydroxy-2-imidazolidinone), dimethylol urea(DMU, bis[N-hydroxymethyl]urea), dihydroxyethylene urea (DHEU,4,5-dihydroxy-2-imidazolidinone), dimethylolethylene urea (DMEU,1,3-dihydroxy-methyl-2-imidazolidinone), and dimethyldihydroxyethyleneurea (DDI, 4,5-dihydroxy-1,3-dimethyl-2-imidazolidinone).

Suitable crosslinking agents include dialdehydes such as C₂-C₈dialdehydes (e.g., glyoxal), C₂-C₈ dialdehyde acid analogs having atleast one aldehyde group, and oligomers of these aldehyde and dialdehydeacid analogs as described in U.S. Pat. Nos. 4,822,453; 4,888,093;4,889,595; 4,889,596; 4,889,597; and 4,898,642. Other suitabledialdehyde crosslinking agents include those described in U.S. Pat. Nos.4,853,086; 4,900,324; and 5,843,061.

Other suitable crosslinking agents include aldehyde and urea-basedformaldehyde addition products. See, for example, U.S. Pat. Nos.3,224,926; 3,241,533; 3,932,209; 4,035,147; 3,756,913; 4,689,118;4,822,453; 3,440,135; 4,935,022; 3,819,470; and 3,658,613.

Suitable crosslinking agents include glyoxal adducts of ureas, forexample, U.S. Pat. No. 4,968,774 and glyoxal/cyclic urea adducts asdescribed in U.S. Pat. Nos. 4,285,690; 4,332,586; 4,396,391; 4,455,416;and 4,505,712.

Other suitable crosslinking agents include carboxylic acid crosslinkingagents such as polycarboxylic acids. Polycarboxylic acid crosslinkingagents (e.g., citric acid, propane tricarboxylic acid, and butanetetracarboxylic acid) and catalysts are described in U.S. Pat. Nos.3,526,048; 4,820,307; 4,936,865; 4,975,209; and 5,221,285. The use ofC₂-C₉ polycarboxylic acids that contain at least three carboxyl groups(e.g., citric acid and oxydisuccinic acid) as crosslinking agents isdescribed in U.S. Pat. Nos. 5,137,537; 5,183,707; 5,190,563; 5,562,740,and 5,873,979.

Polymeric polycarboxylic acids are also suitable crosslinking agents.Suitable polymeric polycarboxylic acid crosslinking agents are describedin U.S. Pat. Nos. 4,391,878; 4,420,368; 4,431,481; 5,049,235; 5,160,789;5,442,899; 5,698,074; 5,496,476; 5,496,477; 5,728,771; 5,705,475; and5,981,739. Polyacrylic acid and related copolymers as crosslinkingagents are described U.S. Pat. Nos. 5,549,791 and 5,998,511. Polymaleicacid crosslinking agents are described in U.S. Pat. No. 5,998,511.

Specific suitable polycarboxylic acid crosslinking agents include citricacid, tartaric acid, malic acid, succinic acid, glutaric acid,citraconic acid, itaconic acid, tartrate monosuccinic acid, maleic acid,polyacrylic acid, polymethacrylic acid, polymaleic acid,polymethylvinylether-co-maleate copolymer,polymethylvinylether-co-itaconate copolymer, copolymers of acrylic acid,and copolymers of maleic acid.

Other suitable crosslinking agents are described in U.S. Pat. Nos.5,225,047; 5,366,591; 5,556,976; 5,536,369, 6,300,259, and U.S.application Ser. No. 08/509,401, to Graef et al.

Suitable catalysts can include acidic salts such as ammonium chloride,ammonium sulfate, aluminum chloride, magnesium chloride, magnesiumnitrate, and alkali metal salts of phosphorous-containing acids. In oneembodiment, the crosslinking catalyst is sodium hypophosphite. Mixturesor blends of crosslinking agents and catalysts can also be used.

The crosslinking agent is applied to the cellulosic fibers in an amountsufficient to effect intrafiber crosslinking. The amount preferablyapplied to the cellulosic fibers can be from about 0.1 to about 10percent by weight based on the total weight of fibers. Higherconcentrations can be employed but may not be practical in a productionenvironment. In one embodiment, crosslinking agent is applied in anamount from about 4 to about 6 percent by weight based on the totalweight of fibers.

The term “hydrophobic material” includes, but is not limited to, latex,sizing agents used to treat pulp such as alkyl ketene dimer or alkenylsuccinic anhydride, rosins, and synthetic rosins, waxes, oils, or otherchemicals that react with the fiber and render the surface hydrophobic.The term “mineral particulate” includes, but is not limited to, clay,calcined clay, calcium carbonate, calcium sulfate, zinc oxide, talc,titanium dioxide, silicas, fly ash, sodium aluminosilicates, or otherminerals. The term “superplasticizer” includes, but is not limited to,polymers that contain sulfonic acid groups, modified lignosulfonates,sulfonated melamine-formaldehyde condensates, sulfonatednaphthalene-formaldehyde condensates, and polycarboxylate derivatives.An example of a commercial superplasticizers include Boral MaterialsTechnology Boral SP, a sulfonated naphthalene-formaldehyde condensate.The term “foam” includes, but is not limited to, foaming agents, foamedmaterial, and foams disclosed in U.S. application Ser. No. 09/569,380,to Graef et al., which are expressly incorporated herein by reference.The term “water reducing agent” includes, but is not limited to, watersoluble adhesives. and plasticizers. An example of a commercial waterreducing agent is methyl cellulose.

The treatment supply source 48 may also deliver more than one treatmentsubstance, and may deliver treatment substances in any number of stepsor stages. For instance, the treatment substance may include bindermolecules and particles, where the binder molecules are first applied tothe fibers and then the particles are added to the binder moleculecoated fibers thus binding the particles to the fibers (as disclosed inU.S. Pat. No. 5,641,561, to Hansen et al., which is expresslyincorporated herein by reference). Other fiber treatment substances andmethods known in the art may be used without departing from the presentinvention.

In addition to the embodiment described above, the pulp supply station40 may be adapted so that the water contained in the pulp supply source42 is exchanged for a solvent treatment substance. The term “solvent”includes, but is not limited to, alcohols, ketones, ethers, alkanes,aromatics, aldehydes, or other classes of organic materials. The solventused may be recovered at the fiber separation station 100.

Additional treatment substances may be added to cause an in situprecipitation. When in situ precipitation is desirable, a first mineraltreatment substance is added to the pulp, then a second treatmentsubstance is added to the pulp. The first and second treatmentsubstances react to form a precipitate treatment substance. For example,dissolved calcium hydroxide may be used as the first treatment substanceand dissolved sodium bicarbonate may be used as the second treatmentsubstance. The calcium hydroxide and sodium bicarbonate react toprecipitate calcium carbonate. Other precipitate treatment substancesmay be formed for treating the pulp including, but not limited to,calcium aluminum silicates, calcium aluminum carbonates, calciumaluminum phosphates, or other mineral precipitates.

The pulp supply station 40 may include a second dewatering device 50.The second dewatering device 50 is inserted in pulp feed conduit 44 tobe in flow communication with the first dewatering device 46. The seconddewatering device 50 may include, but is not limited to, devices such asa screw press, belt press, continuous centrifuge, batch centrifuge,double roll press, or other similar device. Like the first dewateringdevice 46, the second dewatering device 50 removes a portion of thefluid so the feed pulp has a consistency of 10%-55%, preferably 30%-50%prior to drying the feed pulp by the jet drier 20. The partiallydewatered feed pulp is then transported to the jet drier 20 by pulp feedconduit 44. Alternatively, the second dewatering device 50 itself mayserve as a conveyance device. For example, a screw press could be usedto simultaneously dewater and transport the feed pulp to the jet drier20.

The second dewatering device 50 further dewaters the treated feed pulp,potentially removing a portion of the treatment substance from the pulp.To recover a portion of the separated treatment substance, a treatmentrecycle conduit 52 may be connected in flow communication between thesecond dewatering device 50 first dewatering device 46, and/or thetreatment supply source 48. The incorporation of treatment substancewith the pulp may be accomplished through the agitation supplied by thefirst and/or second dewatering devices 46 and 50.

Alternatively, the pulp supply station 40 may include a holding tankdevice 54. The holding tank device 54 may be inserted in recycle conduit52 to be in flow communication with the second dewatering device 50. Theholding tank device 54 acts as a reservoir to store separated treatmentsubstance from the second dewatering device 50 and disperse the storedseparated treatment substance to the first dewatering device 46 and/orto the treatment supply source 48.

The pulp supply station 40 may include a second material handling fan 56inserted in flow communication into pulp feed conduit 44. Afterdewatering, the feed pulp may be run through the second materialhandling fan 56 to break apart the larger pieces of feed pulp intosubstantially uniform pieces prior to introduction into the jet drier20. The second material handling fan 56 may be any de-flaking device,including but not limited to, a buster fan, a pin fluffer, a materialhandling fan, or a shredder.

The pulp supply station 40 further includes a pulp feed device 60coupled in flow communication with pulp feed conduit 44 and jet drier 20pulp intake 24. The pulp feed device 60 is a wet pulp delivery apparatusthat can produce a regulated continuously consistent supply of feed pulpat a desired feed rate to the pulp intake 24 of the jet drier 20. Thefeed pulp has been previously dewatered and, in some cases, treated. Thefeed rate of feed pulp is a process variable that has a direct effect onprocess air temperature, process air pressure, end product fiberappearance, and end product fiber knot count. The pulp feed device 60 isa device that separates atmospheric air from an environment of a higheror lower pressure inside the jet drier 20 and/or separates ambienttemperatures from an environment of higher temperatures inside the jetdrier 20. The pulp feed device 60 allows a continuous input of feed pulpto pass through to the jet drier 20 with a minimum flow of atmosphericair entering the jet drier 20. It is an air-lock positive displacementdevice.

Referring to FIG. 3, the pulp feed device 60 may be a rotary air lock 62having a rotor 64 with rotor vanes 66 rotatably mounted within a rotorhousing 68. One suitable rotary air lock 62 for use in the presentinvention is a modified stainless steel Prater Industries Rotary AirLock Feeder Model No. PAV-6C having a rotor housing and a CLSD,SS,PAV-6rotor with six rotor vanes. Referring to FIG. 4, the Prater Industriesrotor vanes were supplied from the manufacturer with an end 69 that hadstandard clearance between the end of each vane and the rotor housing 68of less than 0.010 inches. This standard clearance causes the feed pulpto jam between the rotor vanes 66 and the housing 68. Therefore, theRotary Air Lock Feeder was modified to provide a leading edge 69A thatwould shear the pulp and an end profile that would prevent the pulpbetween the end 69 and the housing 68 from rolling into intertwinedbundles. The profile of end 69 can be either flat or beveled rearwardlyand radially inwardly. This modification allows the feed pulp to runthrough the pulp feed device 60 without damaging fibers or jamming thepulp feed device 60 and minimizing air leakage. It was found that a0.030-inch clearance between the leading edge of each vane 66 and therotor housing 68 and a 0.050-inch clearance at the radial centerline ofeach vane 66 minimized jamming, rolling, or air leakage around the rotor64. A clearance between the rotor and the housing from 0.010 to 0.050inches should be effective for minimizing rotor jamming, rolling, andair leakage around the rotor 64.

Referring to FIGS. 2, 5, and 6, a foam feeder 70 may be used in place ofthe pulp feed device 60. The foam feeder 70 produces a regulatedcontinuously consistent supply of foamed feed pulp at a desired feedrate to the pulp intake 24 of the jet drier 20. The foam feeder 70 mixesa surfactant and air with pulp and directly injects a foamed pulpmixture into the jet drier 20. The foam feeder 70 is a mechanical mixerthat takes pulp feed, adds a surfactant treatment substance and air tothe pulp, and mechanically agitates the surfactant to suspend the pulpfibers in a foam medium. The foam feeder 70 includes a mechanical mixermain body 71, a pulp injection port 72, a surfactant injection port 73,an air injection port 74, and a foam outlet conduit 75. The mechanicalmixer main body 71 may be any suitable mechanical mixer known in theart. The pulp injection port 72 is in flow communication between thepulp feed conduit 44 and the mechanical mixer main body 71. The pulpinjection port 72 supplies pulp feed to the mechanical mixer main body71. The surfactant injection port 73 is in flow communication betweenthe treatment supply source 48 and the mechanical mixer main body 71,and is placed in close proximity with the pulp injection port 72. Thesurfactant injection port 73 supplies surfactant treatment substance tothe mechanical mixer main body 71. The air injection port 74 is in flowcommunication between a pressurized air source 79 and the mechanicalmixer main body 71, and is placed in close proximity with the surfactantinjection port 73. The air injection port 74 supplies supply air to themechanical mixer main body 71. The foam outlet conduit 75 is in flowcommunication between the mechanical mixer main body 71 and the jetdrier 20 pulp intake 24. The foam outlet conduit 75 discharges the pulpfibers suspended in foam from the mechanical mixer main body 71 anddelivers them to the jet drier 20 pulp intake 24. To optimize the flowof the pulp fibers suspended in foam from foam outlet conduit 75, thefoam outlet conduit 75 diameter, conduit shape, outlet shape, lengthinserted into the jet drier 20, and/or angle of insertion into the jetdrier 20 may be adjusted. The foam feeder 70 may be a screw pump or anyother suitable device known in the art.

Alternatively, a pulp feed device 65 may feed pulp to the foam feeder 70pulp injection port 72. The pulp feed device 65 may be used where thefoam feeder 70 cannot itself produce a regulated continuously consistentsupply of feed pulp to the jet drier 20. The pulp feed device 65 may bea positive displacement pump or any other suitable device known in theart.

The foam outlet conduit 75 may be sealed to the jet drier 20 pulp intake24 by a pulp intake seal 76. The pulp intake seal 76 may be suppliedwith an air leak conduit 77 connected to the pulp intake seal 76 andrunning from the jet conduit 22 to ambient air. The air leak conduit 77provides a limited path between the jet conduit 22 and ambient air. Theconduit may be supplied with a conventional air valve for adjusting theleakage amount. Without being bound in theory, it is believed that theair leak conduit 77 provides a limited pressure relief to the jetconduit 22 and prevents unstable operating conditions within the jetconduit 22.

Optionally, the foam feeder 70 includes a treatment injection port 78 inflow communication between the treatment supply source 48 and themechanical mixer main body 71. The treatment injection port 78 maysupply an additional treatment substance to the mechanical mixer mainbody 71. The treatment injection port 78 may be located anywhere alongthe mechanical mixer main body 71.

Referring to FIG. 6, one suitable foam feeder 70 for use in the presentinvention is a redesigned and modified mechanical mixer from E.T. OakesCorporation (Oakes mixer) for generating a foam suspension of pulp thatcan be fed into the jet drier. The foam feeder 70 includes a frontstator 80, a rear stator 82, a foaming rotor 84, and a drive shaft 86driven by a motor 87 (shown in FIG. 5). The front stator 80 is connectedabout the pulp injection port 72 and defines a circular plane about thepulp injection port 72. The front stator 80 has multiple circular rowsof teeth 81 extending perpendicularly from the circular plane of frontstator 80. These multiple circular rows of teeth 81 are spaced apart,the spaces forming channels between the rows of teeth 81. The rearstator 82 is connected about the foam outlet conduit 75 and defines acircular plane about the foam outlet conduit 75. The rear stator 82 hasmultiple circular rows of teeth 83 extending perpendicularly from thecircular plane of rear stator 82. These multiple circular rows of teeth83 are spaced apart, the spaces forming channels between the rows ofteeth 83. The foaming rotor 84 defines a circular plane and has multiplecircular rows of teeth 85 extending perpendicularly from both sides ofthe foaming rotor 84. One set of the foaming rotor 84 circular rows ofteeth 85 fit within the channels formed by the front stator 80 circularrows of teeth 81. Likewise the other set of the foaming rotor 84circular rows of teeth 85 fit within the channels formed by the rearstator 82 rows of teeth 83. This allows the foaming rotor 84 to berotatably associated with both the front and rear stators 80 and 82. Thefront and rear stators 80 and 82 are connected together about foamingrotor 84, and the foaming rotor 84 is rotatably associated with both thefront and rear stators 80 and 82. The drive shaft 86 is connected to thecenter of the foaming rotor 84 and runs from the foaming rotor 84,through the foam conduit 75, and to motor 87 (shown in FIG. 5).

Referring now to both FIGS. 5 and 6, as pulp feed is forced from thepulp injection port 72 into front stator 80, the pulp feed contacts thestationary teeth 81 of front stator 80 and the rotating teeth 85 offoaming rotor 84. The pulp is forced out from the pulp injection port 72along the surface of the front stator 80, around the rotating foamingrotor 84, along the surface of the rear stator 82, and out the foamoutlet conduit 75. While the pulp is in contact with the front stator80, the surfactant treatment substance is forced from the surfactantinjection port 73 into contact with the pulp feed front stator teeth 81and the foaming rotor teeth 85. The supply air is also forced from theair injection port 74 into contact with the pulp feed, front statorteeth 81, and the foaming rotor teeth 85. The foaming rotor 84 mixes thepulp feed, surfactant, and air together. The mechanical agitation of thefoaming rotor 84 causes the pulp feed fibers to be suspended in a foam.The foamed pulp feed may then be fed directly into the jet drier 20 viathe foam outlet conduit 75. The consistency of the foamed feed pulp maybe 30% or less.

Referring to FIG. 6, optionally, drive shaft 86 is connected to thecenter of the foaming rotor 84 by an auger head 88. The auger head 88has a generally conical shape, and may have a protrusion 89 from theface of the conical surface of auger head 88. The auger head 88 servesto force the pulp feed from pulp injection port 72 toward the rotatingteeth 85 of foaming rotor 84. The protrusion 89 serves to break up thepulp feed and enhance mixing of the pulp feed with the surfactanttreatment substance.

The Oakes mixer was modified by placing the foam outlet conduit 75 atthe original inlet of the Oakes mixer. Without being bound in theory, ithas been found that superior mixing is achieved when the pulp injectionport 72 has a greater diameter than foam outlet conduit 75. The originaloutlet of the Oakes mixer was enlarged to increase flow of feed pulpinto pulp injection port 72, and to place the feed pulp in contact with.the teeth 85 of rotor 84. The Oakes mixer originally came equipped witha nut for connecting the drive shaft 86 to the center of the foamingrotor 84, which was replaced by the auger head 88 above. Additionally,several rows of teeth ( 81, 83, and 85) were removed from the Oakesmixer to improve mixing and increase throughput.

Referring again to FIG. 2, the air supply station 90 may include an airpump 96 and an air heater 98. The air pump 96 receives supply, air viathe air supply source 92 and is coupled in flow communication with airfeed conduit 94. The air heater 98 is inserted into air feed conduit 94and in flow communication with air pump 96 and the jet drier 20 manifold26 via air feed conduit 94.

The air pump 96 may be a positive displacement high volume air pump thatdelivers the supply air at a positive air pressure and at a fixed volumeto the air heater 98. One suitable air pump 96 for use in the presentinvention is a Roots-Dresser universal rotary lobe blower system (ModelNo. 45 URAI) with inlet silencer type CCF-4 with a paper element, adischarge silencer type Universal SD-4, filtration, and electric 15 hpdrive motor. The flow rate may be 300 SCFM. The delivered pressure maybe 5 psig. The pump speed may be 3176 rpm. The drive motor may run at1800 rpm. The air pump 96 may have a gauge range of 0 psig to 15 psigand it may be fitted with a pressure relief valve set at 6 psig. The airheater 98 heats the supply air and delivers the feed air to the manifold26 of the jet drier 20. The manifold 26 may feed the feed airtangentially into the jet drier 20 conduit 22 loop for the purpose ofcreating turbulence for fiberizing and drying the feed pulp inside thejet drier 20.

The air heater 98 may be a flow through type heater that is controlledto regulate the air temperature supplied to the jet drier manifold 26nozzles that feed the conduit 22. The air heater 98 may be an electricheater, a gas heater, or any other form of heater. One suitable airheater 98 for use in the present invention is a Watlow ElectricImmersion heater Model No. 700-96BD2459 that uses 480 VAC line voltage,and has a pressure rating of 150 psig at 1050° F. The air heater 98 overtemperature protection uses a type K thermocouple and a Watlow Series 92controller. The air heater 98 process temperature regulator uses type Jthermocouples and Watlow Series 965 auto tuning controller. The processair temperature is a process variable that has a direct effect on endproduct fiber. appearance, end product fiber knot count, and finescontent.

Upon exiting the jet drier 20, the outlet air, fibers, and fines may betransported along the outlet flow conduit 30 to be recovered by thefiber separation station 100. The fiber separation station 100 may be avacuum conveyor 110 slidably associated with outlet flow conduit 30through a head box 140. The vacuum conveyor 110 includes a screen 112, afirst roller 118, a second roller 120, a primary fan vacuum box 122, aprimary fan 128, a secondary fan vacuum box 130, and a secondary fan134.

The vacuum conveyor 110 screen 112 is a porous conveyor belt devicewhich passes the outlet air and fines through the screen 112 whilepreventing the flow of fiber through the screen 112. The screen 112 is acontinuous loop rotatably coupled to the first roller 118 and the secondroller 120. The screen 112 thus provides a screen upper portion 113having a screen upper surface 114 and a screen lower surface 116 and ascreen lower portion 117. The outlet flow conduit 30 from the jet drier20 is slidably associated with the vacuum conveyor 110 by the head box140 so that the outlet flow conduit 30 is in flow communication with theupper surface 114 of the screen 112. The outlet flow conduit 30 deliversfibers, fines, and outlet air to the upper surface 114. The screen 112passes the outlet air through the upper surface 114 while retainingfibers on the upper surface 114. A fraction of the fines may be passedthrough the screen 112. Alternatively, the screen 112 may collect thefines by trapping them in the fibers as the fibers are retained underthe outlet flow conduit 30 on the moving conveyor screen 112. Thistrapping of fines may result in a level of fines and opacity that doesnot require subsequent fines removal at the fines removal station 170.The rotating screen 112 transports the fibers from the outlet flowconduit 30 toward the fiber collection station 160, defining an upstreamto downstream flow of fibers.

Referring to FIGS. 7 and 8, the primary fan vacuum box 122 is a plenumthat allows passage of outlet air and fines from the outlet flow conduit30 through the screen to the primary fan 128. Referring to FIG. 7, theprimary fan vacuum box 122 has an inlet 124 and an outlet 126. Theprimary fan vacuum box inlet 124 is positioned below the screen 112upper portion 113 and slidably associated with the lower surface 116 ofscreen 112 directly under the head box 140, and is thus in flowcommunication with outlet flow conduit 30 through head box 140 andscreen 112. The inlet to the primary fan vacuum box 122 is matched insize to the head box 140 to allow the head box 140 to seal against theprimary fan vacuum box 122 conduit opening while allowing the screen 112to freely pass therebetween without allowing tramp air to affect thevacuum generated by the primary fan 128.

Referring to FIG. 2, the vacuum conveyor 110 primary fan 128 is coupledin flow communication between the primary fan vacuum box outlet 126 andfines conduit 172. The primary fan 128 pulls the outlet air from theoutlet flow conduit 30, through the head box 140, through the screen 112upper surface 114, through the primary fan vacuum box 122, and to theprimary fan 128 for expulsion to fines conduit 172. The primary fanvacuum box 122 allows the primary fan 128 to generate enough vacuum onthe jet drier 20 to transport the fiber from the jet drier 20 to thescreen 112. The porous conveyor screen 112 retains a portion of thefibers from passing through to the primary fan 128. The porous conveyorscreen 112 conveys the fibers away from the outlet flow conduit 30 andtoward the second roller 120 by rotating about the first and secondrollers 118 and 120. The fibers thus form a mat on the screen uppersurface 114.

The vacuum or negative pressure is defined herein as the null. The nullis an internal positive or negative pressure inside the jet drier 20that is measured in the centrifugal part of the process air stream nearthe pulp intake 24 and between the pulp intake 24 and the fiber outlet28 of jet drier 20. The null is a process control variable that has adirect effect on the through put of the jet drier 20 and the knot countof the fibers. The main variables that affect null are as follows: thevacuum generated by the primary fan 128 on the jet drier 20, feed rateof the feed pulp into the jet drier 20, moisture content of the feedpulp, non-uniformity in pulp size and shape, screen 112 speed and meshsize, pulp type and treatment, damper settings on the primary fan 128,and the temperature of process air fed into the jet drier 20 at themanifold 26. The screen 112 speed is a process control variable that hasa direct effect on null. The rate at which the screen 112 transports thefibers from the outlet flow conduit 30 determines the thickness of theretained fibers being formed on the upper surface 114 of screen 112. Thethickness of the retained fibers may constrict the volume of outlet airflowing through the system thus affecting the null. The jet drier 20null is preferably maintained from 0 to −10 inches of water.

The primary fan 128 may be a side intake, high temperature, high volumeexhaust fan. One suitable primary fan 128 for use in the presentinvention is a steel high temperature side intake material handling fanwith a 10 hp motor with 460 VAC line voltage and may be connected withairtight seals to the primary fan vacuum box 122. An adjustable damperat the exhaust side controls the level of airflow through the primaryfan 128 which has a direct effect on the jet drier 20 null, andtherefore affects the end product fiber appearance and knot count.

Referring to FIGS. 7 and 8, the secondary fan vacuum box 130 is a plenumthat allows the secondary fan 134 to pull air through the screen 112 toprovide suction on the upper surface 114 of screen 112. Referring toFIG. 7, the secondary fan vacuum box 130 has an inlet 131 and outlet132. The secondary vacuum box inlet 131 is slidably associated with thelower surface 116 of the screen 112 and is positioned below the upperportion 113 of screen 112 downstream from the primary fan vacuum box122. The inlet to the secondary fan vacuum box 130 is positioned justdownstream of the terminus of the head box 140. The secondary vacuum boxoutlet 132 is in flow communication with the secondary fan 134.

It will be understood that although the vacuum conveyor 110 has beendescribed as having primary and secondary fans 128 and 134, a single fandevice with dampers may serve as both the primary and secondary fans 128and 134 without departing from the present invention. The fan vacuumboxes 122 and 130 may have a honeycomb shaped baffle to distribute theintake of fresh air through the mat of fibers on the screen upperportion 113.

Referring to FIG. 2, the vacuum conveyor 110 secondary fan 134 iscoupled in flow communication between the secondary fan vacuum boxoutlet 132 and fines conduit 172. The secondary fan 134 provides avacuum which pulls on the retained fibers being conveyed on the uppersurface 114. The secondary fan 134 pulls air through the screen 112,through the secondary fan vacuum box 130, and to the secondary fan 134for expulsion to fines conduit 172. The porous conveyor screen 112prevents the fibers from passing through to the secondary fan 134. Thesecondary fan 134 retains the fibers on the screen 112 while the screen112 is in motion and aids in the extraction and transport of the fibersby creating a vacuum that is strong enough to prevent the primary fan128 from pulling fibers back into the head box 140. Without thesecondary vacuum 134 to hold the fibers in place on the screen 112, thevacuum created by the primary fan 128 in the head box 140 may pull thefibers back into the head box 140. Without the secondary vacuum 134, theresult could be a variable fiber thickness inside the head box 140causing a fluctuation in null resulting in non-uniform deposition offibers, inconsistent fiber separation in the end product, or processshut down because the fibers remain in and plug the head box 140.

The secondary fan 134 may be a side intake low velocity exhaust fan. Onesuitable secondary fan 134 for use in the present invention is a fanmanufactured by Buffalo with a ¼ hp motor with 110 VAC line voltage. Ithas variable speeds and may be connected with airtight seals to thesecondary fan vacuum box 130.

Referring to FIGS. 7 and 8, the vacuum conveyor 110 includes a supportstructure 135. The support structure 135 provides a surface to supportthe moving screen 112. The support structure 135 is shown extendingbetween and supporting the first roller 118 and the second roller 120,along the same plane as that of the screen lower surface 116. Theopenings of the vacuum boxes are located in the support surface 135. Itwill be understood that although shown as a single object, the supportstructure 135 may comprise many separate support structures unassociatedwith one another.

The vacuum conveyor 110 may optionally include a screen vacuum 137. Thescreen vacuum 137 removes any residual fibers from the screen 112 beforethe screen 112 receives new fibers from outlet flow conduit 30. Thescreen vacuum 137 may be located anywhere along screen 112 after thefiber has been removed. In one embodiment, the screen vacuum 137 is avacuum manifold slidably associated with the upper surface 114 of screen112 upstream of the head box 140. One suitable screen vacuum 137 for usein the present invention is a Sears Shop Vacuum and an unmodified vacuumattachment. Alternatively, the primary fan 128 may be used as the vacuumsource for the screen vacuum 137. In another embodiment, an air supplydevice may be positioned on the opposite side of screen 112 from thescreen vacuum 137 to force air through the screen 112 and into thescreen vacuum 137.

The vacuum conveyor 110 may optionally include a separation device 138.The vacuum conveyor 110 separator device may be a thin physical barrierrunning across and slidably associated with the upper surface 114 of thescreen 112 above the downstream end of the secondary vacuum box 130. Theseparation device 138 serves to loosen the retained fibers from theupper surface 114 of the screen 112 so that the fibers may easily beremoved from the screen 112, for instance by gravity, at the vacuumconveyor 110 terminal end adjacent roller 120. The separator device 138may also separate the fibers from the screen 112 and re-lay them on thescreen 112. The fibers may then be collected at the fiber collectionstation 160 into a bulk mass which can be compressed into a bale forshipping to a customer. One suitable separation device 138 for use inthe present invention is a blade made from a Teflon sheet 0.030 inchesthick by 2 inches wide placed at a 45 degree angle across the screen 112at the downstream end of the secondary fan vacuum box 130 and secured atboth ends of the separation device 138 to the support structure 135.

Alternatively, the separation device 138 may be a gas blowing deviceoperatively associated with the screen 112 and located beneath thescreen 112 downstream from the secondary vacuum box 130. The gas blowingseparation device 138 would force gas up through screen 112 to separatethe fibers from the screen.

The fiber separation station 100 includes a head box 140 coupled to theend of the outlet flow conduit 30 for slidably associating outlet flowconduit 30 with screen 112. The head box 140 is an apparatus where theseparation of entrained fibers and outlet air occurs. In one embodiment,the head box 140 has a vacuum tight seal against upper surface 114 ofthe screen 112 where the outlet air and fines are removed. The fibersare trapped on the moving screen 112 and the outlet air and fines passthrough the mat of fiber and through the screen 112.

Referring to FIG. 9, the head box 140 includes a head box shell 142, anout feed roller 145, and a dynamic lip seal 146. The head box shell 142is in flow communication between the outlet flow conduit 30 and theupper surface 114 of the screen 112. The head box 140 out feed roller145 is positioned at the downstream end of head box shell 142 (alsoreferred to as the outlet side of the head box shell 142). The head box140 out feed roller 145 is rotatably and movably coupled to the head boxshell 142 and rollably associated with the upper surface 114 of thescreen 112. The dynamic lip seal 146 is positioned above the out feedroller 145 at the downstream end of box shell 142. The dynamic lip seal146 is hingedly coupled to the head box shell 142 and slidablyassociated with the out feed roller 145.

The head box 140 may be composed of a low friction material wherevermoving parts are in contact. For instance, the head box shell 142 may becomposed of Teflon where the head box shell 142 contacts the screen 112.Additionally, the head box shell 142 may be composed of Teflon where thehead box shell 142 contacts the out feed roller 145.

The head box shell 142 preferably includes vertically oriented slots143. The axles of the out feed roller 145 are positioned in the slots143. The slots 143 allow the out feed roller 145 to move in an up anddown manner to adjust for the varying thickness of the fibers on screen112.

The out feed roller 145 is positioned at the downstream end of head box140 to provide a force for pulling the fibers along the screen 112 andout of the head box 140. The out feed roller 145 may otherwise be a beltor rotor or other similar device. The out feed roller 145 may be poweredby any conventional source. The bottom surface of the out feed roller145 provides an additional force for pulling the fibers along the screen112 and out of the outlet flow conduit 30. The out feed roller 145 maybe made from Teflon-coated steel.

The dynamic lip seal 146 allows the head box 140 to maintain a vacuumtight seal against upper surface 114 of the screen 112. The dynamic lipseal 146 seals the out feed roller 145 to the head box shell 142. Thisdesign allows the out feed roller 145 to rotate and travel vertically tocompensate for non-uniform fiber thickness at the out feed of the headbox 140, without drawing tramp air from around the out feed roller 145.The dynamic lip seal may be made from an inflexible piece 147 joined toa flexible piece 149 by a pivot portion 148. The pivot potion 148 isrotatably coupled to the head box shell 142. The inflexible piece 147moves up and down in response to the motion of out feed roller 145. Theflexible piece 149 allows the inflexible portion to move whilemaintaining a vacuum seal against the head box shell 142. The inflexiblepiece 147 and the flexible piece 149 may be formed of Teflon havingdiffering thickness.

Optionally, the head box 140 further may include a pair of drive wheels150 for driving the out feed roller 145. The drive wheels 150 arerotatably coupled to the upstream end of head box shell 142 in drivingcommunication with the out feed roller 145 and also in mechanicalcommunication with the screen 112. The drive wheels 150 rotate inresponse to the movement of screen 112 and transfer that movement to theout feed roller 145 to rotate the out feed roller 145. The drive wheels150 drive the out feed roller 145 with the use of a coupling device 151.The coupling device 151 may be a chain coupling or any other devicecapable of mechanically associating the drive wheels 150 and out feedroller 145 to turn in unison. It is preferred that the drive wheels 150be coupled to the out feed roller 145 at a 1:1 ratio, to enable thesurface of out feed roller 145 to rotate at the same rate as screen 112.

The head box 140 may also include a height adjustment structure 154. Theheight adjustment structure 154 is connected to the head box shell 142and to the support structure 135. The height adjustment structure 154enables space between the head box shell 142 and screen 112 to beadjusted. The height adjustment structure 154 includes a frame 155, anadjustment nut 156, and an adjustment bolt 157. The frame 155 isconnected to the head box shell 142. The adjustment bolt 157 isconnected to the support structure 135. The adjustment nut 156 isadjustably connected to the adjustment bolt 157 and is also connected tothe frame 155. As the adjustment nut 156 is adjusted along theadjustment bolt 157. The adjustment nut 156 acts on the frame 155 toincrease or decrease the space between the head box shell 142 and screen112.

Alternatively, the fiber separation station 100 may be a cyclone, baghouse, or other similar device for removing fines and fiber togetherfrom outlet air. The fiber separation station 100 may then recycle theseparated outlet air back to the air supply station 90. In thisembodiment, the fines removal station 170 may be located upstream alongconduit 30 to remove the fines from the fibers prior to the fibers beingrecovered at the fiber separation station 100.

Referring again to FIG. 2, the drying system 10 fines removal station170 receives outlet air and fines from the fiber separation station 100.The fines removal station 170 is coupled in flow communication with thefines conduit 172 and the air conduit 182. The fines removal stationreceives fines and outlet air from fines conduit 172, removes at least aportion of the fines, and discharges the outlet air to the air conduit182. The fines removal station 170 may then recycle the outlet air backto the air supply station 90. The fines removal station 170 may be acyclone, bag house, or other similar device.

Alternatively, the fines removal station 170 is coupled to the outletflow conduit 30 between the jet drier 20 and the fiber separationstation 100. The fines removal station 170 in this embodiment mayinclude a cyclone similar to that used as a dust collector for sawdustin wood shops. The fines removal station 170 receives outlet air, fines,and fibers from the jet drier, removes at least a portion of the fines,and sends the fiber coming from the jet drier 20 to the fiber separationstation 100. The fines removal station 170 of this embodiment mayfurther include a second cyclone, bag house, or other similar devicelocated at the primary and secondary fan 128 and 134 outlets. Thissecond cyclone may also receive the filtered fines exhaust from thefirst cyclone.

The drying system 10 noise reduction station 180 is inserted into airconduit 182 and in flow communication with the fines removal station 170via air conduit 182. The noise reduction station 180 provides areduction in the noise produced by the drying system 10. The noisereduction station 180 receives outlet air from the fines removal station170 via air conduit 182, absorbs kinetic energy from the outlet air, anddischarges the outlet air via air conduit 182. The discharged outlet airmay be vented to the atmosphere or recycled to the air supply station90.

Alternatively, the noise reduction station 180 is directly coupled tothe primary and secondary fans 128 and 134. The noise reduction station180 may be a cyclone ducted to the exhaust from the primary fan 128. Theexhaust from the primary fan 128 is discharged into the input side ofthe cyclone and the cyclone outlet ports are independently vented toatmosphere. The exhaust from the secondary fan 134 may be vented to thecyclone or to the cyclone outlet ports. Additionally, the fines removalstation 170 may also serve as a noise reduction station.

Referring to FIG. 13, to produce crosslinked fibers, the drying system10 may optionally include a curing station 310. The curing station 310receives fibers from the fiber separation station 100. The crosslinkertreated fibers are cured in the curing station 310. Optionally, thecrosslinker containing fibers are sent directly to the fiber collectionstation 160 along flow path 158, but only if the crosslinker isadequately cured in the jet drier 20. However, complete crosslinking inthe jet drier may not be achieved in the relatively short time in whichthe fibers conventionally transit through the drier. In one embodiment,the curing station 310 includes a curing oven 320 operatively associatedwith the fiber separation station 100 to receive fibers from the fiberseparation station 100. The curing oven 320 is coupled in flowcommunication with the fiber collection station 160. The fibers from thefiber separation station 100 are delivered to the curing oven 320, thecuring oven 320 cures the crosslinker treated fibers, and the curedfibers are sent to the fiber collection station 160.

Referring to FIG. 14, the curing station 310 alternatively includes aflash drier 340 in addition to curing oven 320. The flash drier 340 isoperatively associated with the fiber separation station 100 to receivecrosslinker treated fibers from the fiber separation station 100. Theflash drier 340 further dries the crosslinker treated fibers. The curingoven 320 is operatively associated with the flash drier 340 to receivethe further dried fibers from the flash drier 340. The curing oven 320is also coupled in flow communication with the fiber collection station160. The fibers from the flash drier 340 are delivered to the curingoven 320, the curing oven 320 cures the further dried fibers, and thecured fibers are sent to the fiber collection station 160.

It will be understood that although the fiber collection station 160 andthe curing station 310 have been described as being separate devices,the fiber collection station 160 and the curing station 310 may be aunitary device. For instance, the vacuum conveyor 110 may be equipped sothat the screen 112 passes through a curing oven 320.

The drying system 10 described above forms singulated and dried fibers.The process takes wet pulp directly from a pulp mill and produces asingulated product from the never-dried pulp by using a drying processthat singulates the pulp directly. This avoids the intermediate steps ofthe pulp drier, handling of the pulp reels and rolls, and hammermillingin a traditional process. The drying system 10 produces fibers having alow knot and fines content. These fibers also have physicalcharacteristics such as kink, curl, and individual twist that are morepronounced than fibers processed by hammermilling. The drying system 10may also produce fibers that have been treated with a treatmentsubstance. The treatments that can be performed on the pulp may bedifficult or impossible to perform on a roll of dried pulp. Treatmentscan be done on the pulp that reduce the amount of knots, increaseproduction rate, and/or form fibers having desirable characteristics.

Where the fibers have been treated with a crosslinker, it is preferredthat the dried, crosslinked, and singulated fibers produced in dryingsystem 10 have a knot count equal to or less than 15%, more preferablyequal to or less than 10%, more preferably equal to or less than 5%, andmost preferably equal to or less than 2%. Where the fibers have beentreated with an additional treatment substance selected from the groupconsisting of surfactant or mineral particulate material, the fibershave a knot count equal to or less than 15%, more preferably equal to orless than 10%, more preferably equal to or less than 5%, and mostpreferably equal to or less than 2%.

It is preferred that the dried, crosslinked, and singulated fibersproduced in drying system 10 have a fines count equal to or less than21%, more preferably equal to or less than 15%, and most preferablyequal to or less than 13%. Where the crosslinked fibers have beenfurther treated with a treatment substance of surfactant, the fibershave a fines count equal to or less than 21%, preferably equal to orless than 15%, and more preferably equal to or less than 13%. Where thecrosslinked fibers have been further treated with a treatment substanceof mineral particulate, the fibers have a fines count equal to or lessthan 21%.

It is preferred that the dried, crosslinked, and singulated fibersproduced in drying system 10 have low knot counts, high accepts counts,and low fines counts. The crosslinked fibers have a knots count equal toor less than 5%, an accepts count equal to or greater than 80%, and afines count equal to or less than 15%; preferably a knots count equal toor less than 5%, an accepts count equal to or greater than 80%, and afines count equal to or less than 13%; more preferably a knots countequal to or less than 5%, an accepts count equal to or greater than 85%,and a fines count equal to or less than 15%; and most preferably a knotscount equal to or less than 2%, an accepts count equal to or greaterthan 80%, and a fines count equal to or less than 15%. Where thecrosslinked fibers have been additionally treated with a treatmentsubstance of surfactant, the fibers have a knots count equal to or lessthan 5%, an accepts count equal to or greater than 80%, and a finescount equal to or less than 15%; preferably a knots count equal to orless than 5%, an accepts count equal to or greater than 80%, and a finescount equal to or less than 13%; more preferably a knots count equal toor less than 5%, an accepts count equal to or greater than 85%, and afines count equal to or less than 15%; and most preferably a knots countequal to or less than 2%, an accepts count equal to or greater than 80%,and a fines count equal to or less than 15%. Where the crosslinkedfibers have been additionally treated with a treatment substance ofmineral particulate, the fibers have a knots count equal to or less than2%, an accepts count equal to or greater than 77%, and a fines countequal to or less than 21%; and preferably a knots count equal to or lessthan 1.6%, an accepts count equal to or greater than 77%, and a finescount equal to or less than 21%.

It is preferred that the dried, crosslinked, and singulated fibersproduced in drying system 10 have a density from 15 kg/m³ to 100 kg/m³,more preferably a density from 25 kg/m³ to 70 kg/m³, and most preferablya density from 30 kg/m³ to 60 kg/m³. These fibers may later be pressedinto a more compact form if desired.

The dried, crosslinked, and singulated fibers produced in drying system10 may be used in any number of end products including but not limitedto absorbent articles, concrete products, plastic products, filterproduct, and paper products. Referring to FIG. 10, the absorbent article210 includes a pervious top portion 212, an impervious bottom portion214, and an absorbent layer 216 located between the pervious top portion212 and the impervious bottom portion 214. The absorbent layer 216includes singulated and dried fibers 218. It will be understood that theterm “absorbent article,” as used herein, includes but is not limited todiapers, tampons, sanitary napkins, incontinence guards, bandages, andmeat and poultry pads.

Referring to FIG. 11, the concrete product 220 includes a concretematrix 226 having singulated and dried fibers 228 incorporated therein.It will be understood that the term “concrete products,” as used herein,includes but is not limited to cement, concrete, mortars, precastmaterial, high strength cement products, extruded cement products,gypsum products, and any other cementitious material. It will beunderstood that while FIG. 11 has been illustrated as a concrete product220, FIG. 11 may also show a plastic product 220 including a plasticmatrix 226 having singulated and dried fibers 228 incorporated therein.It will be understood that the term “plastic products” as used hereinincludes, but is not limited to, plastics and rubbers.

Referring to FIG. 12, the paper product 230 includes a paper sheet 236having singulated and dried fibers 238 incorporated therein. It will beunderstood that the term “paper products,” as used herein, includes butis not limited to paper and paperboard. It will be understood that whileFIG. 12 has been illustrated as a paper product 230, FIG. 12 may alsoshow a filter product 230 having singulated and dried fibers 238incorporated therein.

EXAMPLES

In the processing of pulp into dry singulated fibers used in theexamples below, several process conditions were evaluated. The effectsof variations in the jet drier temperature, feed rate, treatmentapplication, types of pulp, feed rate, and pre-drying dewatering methodswere all explored in the examples below.

Unless otherwise noted, the apparatus used for the examples below is asfollows: pulp was dried and singulated into fibers using a Fluid EnergyAljet Model 4 Thermajet X0870L jet drier. No modifications were made tothe Model 4 Thermajet. The pulp was fed to the jet drier in severaldifferent apparatuses. For large runs a shaftless screw conveyormanufactured by Martin Sprocket and Gear, Inc., Martin ConveyorDivision, was used. It had a hopper at the lower end of the conveyor forplacing the wet pulp and conveyed the wet pulp up an incline that roseup towards the pulp feed device on the jet drier. For runs of lowquantities of pulp, a Weyerhaeuser designed and manufactured conveyorwith hopper type feeder for feeding wet pulp was used. For feedingfibers suspended in a foam medium, a Weyerhaeuser redesigned andmodified, Oakes mixer was used to directly inject foamed pulp into thejet drier.

In Examples 1-9, the feed pulp used was a pressed wet web of pulp havinga basis weight of a substantial amount to provide sufficient stiffnessto feed the web into a shredding device. The wet web was produced on apilot papermachine that had a spray system attached to it to allowtreatment of the wet web prior to pressing. A basis weight of 500 gsm to1500 gsm was found to work adequately. The web was fed into theshredding device through a rotating and reversible roller nip and into arapidly rotating set of rolls containing protruding pins that tore theweb into small pieces of pulp.

The feed pulp was delivered to the jet drier using a stainless steelPrater Industries Rotary Air Lock Feeder Model No. PAV-6C having a rotorhousing and a CLSD,SS,PAV-6 rotor with six rotor vanes. The refittedrotor was a custom modified six vane closed end rotor that was reducedin diameter to give more clearance between the vane and rotor housing sowet pulp could be run through the feeder without damaging fibers orjamming the rotor.

The feed air was delivered to the jet drier with a Roots-Dresseruniversal rotary lobe blower air pump with silencer and filtration,Model No. URAI. The flow rate was 300 SCFM. The delivered pressure was 5psig. The pump speed was 3176 rpm. The drive motor was an electricLincoln 15 hp that was running at 1800 rpm. The air pump had an inletsilencer type CCF-4 with a paper element and a discharge silencer typeUniversal SD-4. The assembly had a gauge range of 0 psig to 15 psig andit was fitted with a pressure relief valve set at 6 psig.

The feed air was heated with a Watlow Electric Immersion air heater,Model No. 700-96BD2459. The air heater used 480 VAC line voltage, andhad a pressure rating of 150 psig at 1050° F. The over temperatureprotection used a type K thermocouple and a Watlow Series 92 controller.The process temperature regulator used type J thermocouples and WatlowSeries 965 auto tuning controller.

A material handling fan (MHF) was placed in the ducting between the jetdrier and the vacuum conveyor. The MHF was used in Examples 1-8, but wasnot used in Examples 9-24.

The outlet air, fibers, and fines were delivered to a custom designedvacuum conveyor via a head box sealed to the conveyor screen. A SearsShop Vacuum with an unmodified vacuum attachment was used for the screenvacuum. The primary fan was a steel high temperature side intakematerial handling fan with airtight seals to the primary fan vacuum box.The primary fan had a 10 hp motor with 460 VAC line voltage. Anadjustable damper at the exhaust side controlled the level of airflowthrough the fan which had a direct effect on the jet drier null, whichcreated a vacuum of −1 to −5 inches of water. The exhaust from theprimary fan discharged into a cyclone that currently serves the purposeof noise reduction. The secondary fan was manufactured by Buffalo andhad a ¼ hp motor with 110 VAC line voltage. The secondary fan hadvariable speeds and was connected with airtight seals to the secondaryfan vacuum box. The secondary fan discharged to the exhaust side of thecyclone. The separation device was made from Teflon sheet 0.030 inchesthick by 2 inches wide placed at a 45 degree angle across the conveyorscreen at the down stream end of the secondary fan vacuum box.

In the examples below, “sonic knots” were tested by the following methodfor classifying dry fluffed pulp into three fractions based on screenmesh size. The first fraction is the knots and is defined as thatmaterial that is captured by a No. 12 mesh screen. The second fractionis the accepts or the singulated fibers and is defined as that materialthat passes through a No. 12 mesh screen but is captured by a No. 60mesh screen. The third fraction is the fines and is defined as thatmaterial that passes through a No. 12 and through a No. 60 mesh screen.The separation is accomplished by sound waves generated by a speakerthat are imposed upon a pre-weighed sample of fluff pulp placed on a No.5 mesh screen that is near the top of a separation column where thespeaker sits at the very top. After a set period of time, each fractionis removed from the separation column and weighed to obtain the weightfraction of knots, accepts/singulated fiber, and fines.

Example 1

Singulated dried Douglas fir fiber and treated dried Southern pine fiberwas produced by making wet rolls of pulp on a pilot papermachine andhand feeding the wet rolls into the shredding device and drier systemdescribed above. Some untreated (as is) bleached Southern pine andDouglas fir rolls were dried. Additional Southern pine rolls weretreated then dried. The treatments on the separate runs of the Southernpine feed pulp were as follows: 1) Citric acid; 2) Glyoxal; 3) Clay; 4)Hydrophobic latex and fly ash; 5) Hydrophobic latex, fly ash, andsuperplasticizer; 6) Glyoxal, hydrophobic latex, fly ash, andsuperplasticizer; 7) Glyoxal, hydrophobic latex, fly ash, methylcellulose, and superplasticizer; 8) no treatment; 9) fly ash; and 10)clay. The feed rate of the pulp was 25 g/min-111 g/min OD (oven dried).The solids content was approximately 28% in the rolls prior to drying.The outlet temperature of the drier ranged from 180° C. to 200° C. Theinlet temperature was varied to attain the outlet temperature. Table 1summarizes these runs and treatments. The clay and fly ash treated pulpappeared to fiberize the best. The pulp with methyl cellulose wasdifficult to run and fiberize. The other runs appeared to fiberizesimilar to untreated pulp. Sonic knots were not measured on thesesamples. TABLE 1 Fiber Treatment. Citric Acid Glyoxal Feed Cross- Cross-Methyl Super- Outlet Rate Linker Linker Latex Clay Fly Ash Celluloseplasticizer temp. G/MIN Run # (XLC) (XLG) (L) (CL) (FA) (MC) (SP) (° C.)OD  1 ✓ 200/180 73.9  2 ✓ 200/180 63.4  3 ✓ 180 29.6  4 ✓ ✓ 200 113.3  5✓ ✓ ✓ 200 69.1  6 ✓ ✓ ✓ ✓ 200 98.8  7 ✓ ✓ ✓ ✓ ✓ 200 95.6  8 180 24.8  9✓ 200 105.4 10 ✓ 200 81.0  0a 200/180 52.5  0b 180 24.8

Example 2

Unbleached and untreated singulated dried fiber was produced by makingwet rolls of unbleached Douglas fir (DF) pulp on a pilot papermachineand hand feeding the wet rolls into the shredding device and driersystem described above. The dried fiber was collected and tested forsonic knots which were 5% at one feed rate (in rpm of the feed rollermotor into the shredder) and 15% at a higher feed rate. The outlettemperature was maintained at 180° C. for both runs. The fines contentwas about 11% at the lower feed rate and 12% at the higher feed rate.The accepts were 83% at the lower feed rate and 74% at the higher feedrate. Table 2 summarizes the data. TABLE 2 Varying feed rate effects onuntreated roll samples. Knots Feed Outlet Run # Pulp (%) Accepts FinesRate Speed Temp. (° C.) 11 DF 14.73 74.13 11.13 300 180 12 DF 5.07 83.0711.87 250 180

Example 3

Bleached and untreated singulated dried fiber samples were produced bymaking wet rolls of bleached Douglas fir pulp on a pilot papermachineand hand feeding the wet rolls into the shredding device and driersystem described above. The dried fiber was collected and tested todetermine the effect of outlet temperature and feed rate on sonic knotsand also the effect on fiber strength as measured by wet zero spantensile strength (ZST). The t86% gives a value to establish the lowerand upper limits of the error range for the ZST results. There was nostatistically significant change in fiber strength. It was found that ahigher feed rate produced a higher amount of knots and a higher outlettemperature produced more knots. Table 3 shows the results. TABLE 3 Jetdrier runs showing effect of temperature and feed rate on knots and ZST.ZST Index Knots Accepts Fines Shredder Outlet Feed Rate Run # (Nm/g)t86% (%) (%) (%) Speed Temp. (° C.) (g OD/min) Control 108 10.6 13 1065.7 20.53 66.87 12.60 300 160 70 14 103 1.4 19.87 65.60 14.53 300 170 7015a 105 4.9 25.00 63.67 11.33 300 180 70 15b 101 4.9 47.33 41.27 11.40500 180 116 15c 95 2.8 6.40 78.33 15.27 125 180 29 16 103 3.5 26.5360.87 12.60 300 190 70 17 99 4.9 41.93 47.20 10.87 300 200 70

Example 4

Bleached and untreated singulated dried Douglas fir fiber samples wereproduced by slushing wet lap and dewatering it by using a centrifuge andthen hand feeding the pulp on a belt conveyor into the drier systemdescribed above. The dried fiber was collected and tested to determinethe effect of various wet pulp preparation methods. The wet pulppreparation methods included centrifuged, centrifuged and pin-fluffed,and centrifuged and wetted. Sonics knot levels were tested and theresults are shown in Table 4 where it can be concluded that justcentrifuging provides the lowest sonic knots at 14.2%. TABLE 4 Jet drierruns showing effect of pulp preparation on sonic knots. Run # SamplePreparation Knots (%) Accepts (%) Fines (%) Inlet Temp. (° C.) 18Centrifuge and Fluffed 17.9 69.5 12.7 220 19 Centrifuged 14.2 71.4 14.4220 20 Centrifuged and Wetted 16.7 70.7 12.6 220

Example 5

Fly ash treated and untreated bleached singulated dried Douglas firfiber samples were produced by slushing wet lap and dewatering it byusing a centrifuge and then hand feeding the pulp on a belt conveyorinto the drier system described above. The fly ash containing pulp wasmade by adding 20% by weight fly ash with high molecular weight anionicretention aid to the slush pulp prior to centrifuging. The dried fiberwas collected and tested to determine the effect of inlet temperatureand fly ash on sonic knots. The results are shown in Table 5 where itcan be seen that fly ash treatment dramatically reduced knots from ahigh of 20% to a low of 1% by weight. Also it can be seen for these runsthat increased inlet temperature and outlet temperature slightly reducedknots. TABLE 5 Singulated Douglas fir pulp with and without fly ash. FlyAsh Knots Accepts Fines Inlet Temp. Outlet Run # Sample Preparation (%)(%) (%) (%) (° C.) Temp. (° C.) 21a Centrifuged, fluffed 20.40 66.7312.87 260 160 21b Centrifuged 14.13 74.40 11.47 260 180 21c Centrifuged,fluffed 16.13 72.93 10.93 300 180 22a Centrifuged, fluffed FA 20% 1.0780.00 18.93 260 180 22b Centrifuged, fluffed FA 20% 1.27 79.00 19.73 230180

Example 6

Singulated dried fiber was produced from never-dried unbleached pulptaken from a double roll press in a commercial mill after deflaking. Thepulp was run as collected from the mill and no treatments were done onit. The results are provided in Table 6 which shows that the knotsranged from 0.75 to 2.37 percent. Increasing outlet temperature bydecreasing feed rate resulted in a slight decrease in knots. Increasinginlet temperature by increasing feed rate increased knots slightly.Washing, centrifuging, and fluffing increased knots slightly. Reheatingthe pulp appeared to have no effect. The “kappa” number is a measure ofthe amount of lignin remaining in the pulp post pulping, and isquantified by the Tappi Standard Test Methods test number T-236. TABLE 6Untreated centrifuged Douglas fir unbleached samples from double rollpress. Effect of kappa #, pulp temperature, and sample preparation.Inlet Outlet Temp. Temp. Run # Pulp Sample Preparation Kappa# KnotsAccepts Fines (° C.) (° C.) 23a DF As-is 25 — — — 230 150 23b DF As-is25 0.90 83.92 15.18 240 150 23c DF As-is 25 1.36 85.95 12.70 250 155 23dDF As-is 25 1.27 83.60 15.13 260 160 23e DF As-is 25 1.80 76.33 21.87300 220 23f DF As-is 25 1.49 80.98 17.53 260 160 23g DF As-is 25 1.2981.04 17.67 260 180 23h DF As-is 25 0.75 84.10 15.15 300 180 24a DFAs-is heated pulp 25 1.16 82.41 16.43 260 160 24b DF As-is heated pulp25 1.97 81.89 16.13 260 180 25a DF As-is 12 2.37 79.21 18.42 260 160 25bDF As-is 12 1.82 82.19 15.99 260 180 25c DF As-is 12 2.31 80.75 16.95300 180 26a DF Washed, Centrifuged, 25 2.60 82.93 14.47 260 160 fluffed26b DF Washed, Centrifuged, 25 1.87 82.80 15.33 260 180 fluffed

Example 7

Bleached and untreated singulated dried fiber samples were produced bymaking wet rolls of bleached Douglas fir pulp on a pilot papermachineand hand feeding the wet rolls into the shredding device and driersystem described above. The knots for this system were high at 34%indicating that feeding pulp directly is better than forming a wet weband shredding the web during feed.

Example 8

Bleached and untreated singulated dried fiber samples were produced bypin-fluffing never-dried Southern pine and feeding the pulp by placingit into a foam feed system where water and surfactant are injected andmixed with the wet pulp providing a flowable mix that can be fed intothe jet drier system. The knots were less than 2%, but the fines amounthad gone up to almost 20% compared to previous runs.

Example 9

An unbleached and untreated singulated dried fiber sample was producedby running the pulp as obtained from a mill in the drying systemdescribed above without the material handling fan between the drier andthe vacuum conveyor. Compared to previous runs, the knots increasedslightly from 1.8% to 3.5% for the same temperatures.

Example 10

An unbleached and untreated singulated dried fiber sample was producedby running the pulp as obtained from a mill in the drying systemdescribed above without the material handling fan between the drier andthe vacuum conveyor. Compared to previous runs, the knots increasedslightly from 1.3% to 2.6% for the same temperatures. A bleached controlsample had a slight increase in knots from 20.4 to 21.9%.

Example 11

A bleached dissolving grade fiber was dried using the drying systemdescribed above. The pulp had about 10% knots. The moisture was lessthan 2%, which is typically too low. Dissolving tests showed that thefiber performed about the same as typical commercial grade pulp.

Example 12

Bleached singulated fiber was produced with the drying system describedabove to compare the effect of the dewatering process on knots.Screwpressed pulp was compared to centrifuged pulp and centrifugedcontrol wet lap pulp. The results are in Table 12 which shows thatcentrifuging provides a lower amount of knots. TABLE 12 Runs todetermine difference between screw-pressed, centrifuged wet lap, andcentrifuged slush. Two levels of spring pressure were used on the press.Inlet Outlet Spring Average Temp. Temp. Run # Sample PreparationPressure Knots % Knots Accetps Fines (° C.) (° C.) 32a Screwpressed High19.3 61.5 19.3 260 180 bleached DF slush 32b Screwpressed High 25.7 61.113.3 280 180 bleached DF slush 32c Screwpressed High 25.6 59.9 14.5 280200 bleached DF slush 32e Screwpressed Low 27.9 57.7 14.3 280 180bleached DF slush 32f Screwpressed Low 22.3 13.3 66.7 20.0 260 180bleached DF slush 33a Control, Centrifuged 20.1 61.7 18.1 260 180 wetlap33b Control, Centrifuged 16.6 65.5 17.9 270 200 wetlap 33c Control,Centrifuged 26.3 59.1 14.5 280 180 wetlap 33d Control, Centrifuged 21.121.3 65.1 13.6 280 200 wetlap 34a Centrifuged Slush 20.8 64.0 15.2 260180 34b Centrifuged Slush 15.6 68.0 16.4 260 200 34c Centrifuged Slush14.6 67.9 17.5 280 180 34d Centrifuged Slush 17.6 19.2 67.5 13.3 280 200

Example 13

Crosslinked bleached singulated fiber was produced with the dryingsystem described above to determine the ability of the drier to runcrosslinked treated pulp. As with other grades of pulp, a low amount ofknots is desirable with crosslinked pulp. Two runs were done atdifferent temperatures as shown in Table 13. Polyacrylic acid (PAA XL)was added to the pulp at approximately 5% by weight on pulp. Post curingwas done to complete the reaction. The data shows that the highertemperature in the jet drier lowered sonic knots slightly and loweredwet knots also. Post cure time increased wet knots and may haveincreased sonic knots. The level of sonic knots is considerably higherthan untreated pulp indicating that the polyacrylic acid treatmentincreases knots. Rewetting the crosslinked pulp and drying in an ovenshowed that the pulp did not bond to itself indicating crosslinking ofthe pulp. TABLE 13 Five percent polyacrylic acid treated pulp. InletOutlet Sample Post Cure Sonic Wet Knots Temp. Temp. Run # PreparationTime (min) Knots (% Rejects) Accepts Fines (° C.) (° C.) 35a bleached 035.00 0.0 48.33 16.67 286 200 never-dried w/PAA XL bleached 2 32.0715.35 56.87 11.07 286 200 never-dried w/PAA XL bleached 3.5 28.93 16.0258.60 12.47 286 200 never-dried w/PAA XL bleached 5 23.80 18.24 62.1314.07 286 200 never-dried w/PAA XL 35b bleached 0 28.07 0.26 55.00 16.93296 210 never-dried w/PAA XL bleached 2 24.00 14.48 63.00 13.00 296 210never-dried w/PAA XL bleached 3.5 20.40 9.57 65.33 14.27 296 210never-dried w/PAA XL bleached 5 24.67 11.28 63.60 11.73 296 210never-dried w/PAA XL

Example 14

Clay and fly ash treated bleached singulated fiber was produced with thedrying system described above to determine the effect on sonic knots.The clay and fly ash was added at 0%, 1%, and 10% by weight. The sampleswith 10% mineral had less knots. The fly ash containing fibers had lowerknots than the clay containing fibers at the same dosage. The sampleswith 1% mineral do not appear much different than the control. Table 14provides a summary of the data. TABLE 14 Runs to determine effect ofclay and fly ash on knots. Outlet Inlet Temp. Temp. Run # SamplePreparation Mineral % Knots Accetps Fines (° C.) (° C.) 38 Control, wetlap 0 19.13 65.80 15.07 270 180 centrifuged As is 39 Control, wet lap 123.87 63.87 12.27 270 180 centrifuged With Clay 40 Control, wet lap 1010.07 71.27 18.67 270 180 centrifuged With Clay 41 Control, wet lap 115.93 68.00 16.07 270 180 centrifuged With Fly Ash 42 Control, wet lap10 4.00 69.20 26.80 270 180 centrifuged With Fly Ash

Example 15

Singulated fiber was produced using the drying system described abovefrom bleached Douglas fir pulp. The pulp was prepared by centrifugingand then running the pulp through the drier system cold to break apartthe wet chunks of pulp and then feeding the broken apart pulp throughthe drier system hot as normal. The purpose is to determine theefficiency of the drier system to prepare pulp for singulation. Theeffect of outlet temperature on singulation was also tested. Outlettemperature is changed by changing feed rate. At the same outlettemperature, the cold then hot run through the drier reduced knots byhalf. Increasing outlet temperature reduced knots significantly. Theresults are shown in Table 15. TABLE 15 Jet drier runs to determine theeffect of running fiber through the drier system with no heat and thenrunning the same fiber through the system hot. Inlet Outlet ConveyorSonic Temp. Temp. Speed Run # Sample Preparation Knots Accepts Fines (°C.) (° C.) (hz) 46a Control, wet lap centrifuged 20.13 64.93 14.93 260170 4.0 (twice through - cold then hot) 46b Control, wet lap centrifuged7.87 76.80 15.33 260 197 3.0 (twice through - cold then hot) 46cControl, wet lap centrifuged 8.53 76.73 14.73 260 +200  2.25 (twicethrough - cold then hot) 47 Control, wet lap centrifuged 14.53 70.6714.80 260 198 3.5 (once through - hot only)

Example 16

Singulated fiber was produced using the drying system described abovefrom unbleached Douglas fir pulp. The pulp was prepared by centrifugingit in a batch centrifuge. Sonic knots ranged from 2% to 5% over aseveral hour period indicating good system stability. The results areshown in Table 16, where “run ave” is the mean average of all six (46a-46 f) runs. TABLE 16 Jet drier runs to determine system stability.Time Sonic Inlet Outlet Run # into run Knots Accepts Fines Temp. (° C.)Temp. (° C.) 48 Run ave 4.5 84.3 11.2 260 160 48a (1 hour) 5 83 12 260160 48b (2 hour) 4 85 11 260 160 48c (3 hour) 6 84 10 260 160 48d (4hour) 2 87 11 260 160 48e (5 hour) 5 84 11 260 160 48f (6 hour) 5 83 12260 160

Example 17

Singulated fiber was produced using the drying system described abovefrom bleached and unbleached Douglas fir and bleached Southern pinepulp. The pulp was prepared by centrifuging it in a batch centrifuge. Amaterial handling fan was used to break apart the pulp prior to dryingit. Steam heat was used to prepare selected pulps. Different outlettemperatures were also run. The results are shown in Table 17. Steamheating the pulp prior to drying reduced knots. A higher outlettemperature reduced knots. Unbleached pulp had the lowest amount ofknots.

-   -   Table 17: Runs to compare bleached and unbleached Douglas fir        and bleached southern pine singulated fibers, as well as steam        treatment.

Example 18

Singulated fiber was produced using the drying system described abovefrom bleached Douglas fir and bleached Southern pine pulp. The pulp wasprepared by centrifuging it in a batch centrifuge. A material handlingfan was used to break apart the pulp prior to drying it. Passing thepulp through the jet drier system with the heat off was done on selectedsamples. The results are shown in Table 18. Sonic knots ranged from 1.87to 10.07. Running the pulp through the system with the heat off prior todrying the pulp reduced knots. TABLE 18 Bleached Douglas fir andsouthern pine with no treatment but with selected defiberization. InletOutlet Sonic Temp. Temp. Run # Pulp Sample Preparation Knots AcceptsFines (° C.) (° C.) Null 53a B-SP Never-dried, bleached, 1.87 79.9318.20 250 185 −3.5-4.0 slushed, centrifuged, material handling fan Runtwice - cold/hot 53a2 B-SP Never-dried, bleached, 10.07 72.60 17.3 250177 −3.5 slushed, centrifuged, material handling fan Hot only 53a2 subsample-1 9.87 75.33 14.8 53a2 sub sample-2 6.87 74.87 18.2 53a2 subsample-3 9.33 73.47 17.2 53b B-SP Never-dried, bleached, 9.40 72.40 18.2250 171 −3.5 slushed, centrifuged, material handling fan Hot only 54aB-DF Control, wet lap 3.00 82.20 14.80 250 −5   bleached, centrifuged,material handling fan Run twice - cold/hot 54a2 B-DF Control, wet lap,5.87 80.73 13.40 250 177 −3.5-4.0 bleached, centrifuged, materialhandling fan Run twice - cold/hot 54b B-DF Control, wet lap, 9.80 77.6712.53 250 171 −3.5 bleached, centrifuged, material handling fan Hot only

Example 19

Singulated fiber was produced using the drying system described abovefrom bleached Douglas fir treated with 0.1% sodium dodecyl sulfate. Thepulp was prepared by centrifuging it in a batch centrifuge aftertreatment. Passing the pulp through the jet drier system with the heatoff was done on the samples. The results are shown in Table 19. Sonicknots ranged from 0.73% to 2.27% indicating that surfactant treatmentsignificantly reduces sonic knots. TABLE 19 Runs on bleached Douglas firpulp treated with 0.1% sodium dodecyl sulfate. Inlet Outlet Amount SonicTemp. Temp. Run # Sample Preparation (kg) Knots Accepts Fines (° C.) (°C.) 55 Control, wet lap 3 separate 1.07 84.40 14.53 250 180 bleached,slushed in 0.1% bags for 0.73 83.80 15.47 solution of SDS, testing 0.7384.00 15.27 centrifuged only Run twice - cold then hot 56 Control, wetlap 3 separate 1.33 85.00 13.67 240 170 bleached, slushed, bags for 2.2783.93 13.80 centrifuged, material testing 0.87 85.07 14.07 handling fanRun twice - cold then hot 57 Control, wet lap 3 separate 1.00 83.1315.87 240 170 bleached, slushed in 0.1% bags for 1.00 83.67 15.33solution of SDS, testing 1.00 83.93 15.07 centrifuged only Run twice -cold then hot

Example 20

Singulated fiber was produced using the drying system described abovefrom bleached Southern pine (B-SP) with and without latex treatment andfrom unbleached and bleached Douglas fir (U-DF and B-DF, respectively)pulp. The bleached Southern pine pulp was prepared by centrifugingslushed pulp, running it through a material handling fan, and thenrunning it through the jet drier with the heat off prior to drying it.The unbleached Douglas fir was only centrifuged after slushing. Thelatex treated bleached Southern pine pulps were prepared by passing thepulps through the jet drier system with the heat off after treatment andcentrifuging. The bleached Douglas fir control pulp was only centrifugedafter slushing. The results are shown in Table 20. Sonic knots were low.on the bleached Southern pine indicating the mechanical treatmentsreduce knots. The unbleached Douglas fir pulp had the lowest knotsindicating that it fiberizes well in this system. The latex treatedpulps also had low knots showing that the latex may reduce knots or maynot affect their production. The control bleached Douglas fir had lowknots indcating an improvement in the drier system. The latex treatedpulps were hydrophobic. TABLE 20 Singulated Southern pine and Douglasfir pulps run through the drier with no heat. Inlet Sonic Temp. OutletRun # Pulp Sample Preparation Knots Accepts Fines (° C.) Temp. (° C.) 58B-SP Bleached, never-dried, 1.07 81.07 17.87 240 167-170 slushed,centrifuged, material 1.67 79.40 18.93 handling fan 3.67 78.53 17.80 Runtwice - cold then hot 59 U-DF Centrifuged only 0.80 85.73 13.47 240167-170 Run hot only 60 B-SP Latex #1 1.27 88.20 10.53 240 160-165 Runtwice - cold and hot 61 B-SP Latex #2 1.60 84.00 14.40 240 160-165 Runtwice - cold and hot 62 B-SP Latex #3 1.33 84.60 14.07 240 160-165 Runtwice - cold and hot 63 B-SP Latex #4 1.07 84.93 14.00 240 160-165 Runtwice - cold and hot 64 B-DF Control, wet lap bleached, 2.20 83.67 14.13240 167-170 slushed, centrifuged only

Example 21

Singulated fiber was produced using the drying system described abovefrom bleached Douglas fir pulp. The pulps were prepared by centrifugingonly, centrifuging and running through a material handling fan,centrifuging and running through the drier with the heat off beforedrying or adding chemical surfactant prior to centrifuging. The resultsare in Table 21. Pulp that had been centrifuged or centrifuged and runin the material handling fan was about equal in sonic knots at 15%.Running centrifuged pulp through the system with no heat reduced knotsto about 10%. The surfactant treatment reduced knots to about 3%. Theseresults were duplicated in follow-up runs. Conveyor speed was 7 ft/min,null was-3.5 to-4 inches water. TABLE 21 Singulated bleached Douglas firpulp comparing mechanical fiberization pulp preparation to Berol 587kchemical surfactant. Sonic Inlet Temp. Outlet Temp. Feed Run # SamplePreparation Knots Accepts Fines (° C.) (° C.) Rate 65 Control, wet lapbleached, slushed, 15.33 71.47 13.20 260 180 150 centrifuged, materialhandling fan Hot only 66 Control, wet lap bleached, slushed, 9.93 76.1313.93 260 180 150 centrifuged only, Cold then Hot 67 Control, wet lapbleached, slushed, 2.88 85.80 11.32 260 180 150 centrifuged with 1%surfactant Hot only 68 Control, wet lap bleached, slushed, 15.62 72.0312.35 260 180 150 centrifuged only, Hot only

Example 22

Singulated fiber was produced using the drying system described abovefrom bleached Douglas fir pulp and Southern pine pulp with and withoutpolyacrylic acid crosslinker, surfactant, and clay treatments. The pulpswere prepared by centrifuging only or centrifuging and running through amaterial handling fan (MHF) prior to drying. The results are in Table22. The Douglas fir control had 9% knots. The Southern pine withsurfactant had 2% knots confirming the benefit of surfactant. Thepolyacrylic acid only treatment increased knots to 15%. Addingsurfactant or clay to the polyacrylic acid treated pulp reduced knotsbelow 2% demonstrating the benefit of surfactant and clay to reduceknots. The inlet temperature was 240° C. and outlet temperature was 165°C. Null was −3.5 inches of water and conveyor speed was 6.0 ft/min.TABLE 22 Singulated bleached Douglas fir control and Southern pine pulpwith and without polyacrylic acid, surfactant, and clay treatments. ODFeed Rate Run # Pulp Sample Preparation Clay Knots Accepts Fines (g/min)75 B-DF Control, wet lap centrifuged 0 9.00 79.47 11.53 71.02 Hot only76 B-SP Bleached, never-dried, slushed, 0 2.07 84.93 13.00 83.15centrifuged, MHF, with 1% surfactant 77 B-SP Bleached, never-dried,slushed, 0 14.87 65.80 19.33 92.63 centrifuged, MHF, w/20% PAA on fiber78 B-SP Bleached, never-dried, slushed, 0 1.60 85.40 13.00 89.71centrifuged, MHF, w/20% PAA on fiber and with 1% surfactant 79 B-SPBleached, never-dried, slushed, 10 1.20 77.80 21.00 88.07 centrifuged,MHF, w/20% PAA on fiber 80 B-SP Bleached, never-dried, slushed, 20 1.8076.67 21.53 86.91 centrifuged, MHF, w/20% PAA on fiber

Example 23

Singulated fiber was produced using the drying system described abovefrom two different bleached Douglas fir pulps with selected amounts ofBerol 587k surfactant on one of the pulps. One batch of pulp was treatedwith soluble iron. The pulps were prepared by centrifuging only. Theresults are in Table 23. The surfactant worked best at the 1% dosagelevel. The iron reduced knots significantly, but also increased fines toa high level. Feed rate may have had an influence on the surfactantresults. Higher feed rates appeared to increase knots. The inlettemperature was 240° C. and outlet was 160° C. The conveyor speed was 6ft/min and null was −3.5 inches water. TABLE 23 Run to determine minimumamount of surfactant needed to reduce knot content below 2% using thebleached KKT from Kamloops. OD Feed % Sonic Rate Run # Pulp SamplePreparation Surfactant Knots Accepts Fines (g/min) 85 B-DF#2 Control,slushed, 0 4.20 82.07 13.73 75.80 centrifuged only Hot only 86 B-DF#2Slushed, centrifuged, 0.1 4.13 81.00 14.87 108.32 w/surfactant,centrifuged Hot only 87 B-DF#2 Slushed, centrifuged, 0.5 3.73 84.3311.93 90.51 w/surfactant, centrifuged Hot only 88 B-DF#2 Slushed,centrifuged, 1.0 2.00 86.27 11.73 73.25 w/surfactant, centrifuged Hotonly 89 B-DF Wet lap centrifuged 0 1.93 65.27 32.80 71.90 (bleached)with 0.05% Fe3+ 90 B-DF Control, wet lap bleached, 0 5.00 80.67 14.3371.56 slushed, centrifuged —end of run sample Hot only

Example 24

Singulated fiber was produced using the drying system described abovefrom bleached Douglas fir pulp that had been dewatered using ascrewpress. The results are in Table 24. The amount of knots issufficiently low compared to previous runs to show screwpress dewateringis an acceptable option to remove excess water prior to drying with thejet drier system. TABLE 24 Singulated bleached Douglas fir prepared frompulp dewatered through a screwpress. Inlet Outlet Sonic Temp. Temp. Run# Sample Preparation Knots Accepts Fines (° C.) (° C.) Null 91 Control,wet lap bleached, 3.20 85.87 10.93 240 189-190 −3.5 slushed,centrifuged, material handling fan Cold then Hot 92 Never-dried, Screwpressed (HC > 30), 3.87 82.33 13.80 240 169-171 −3.5 to −4.0 materialhandling fan Hot only

Examples 25-29

The pulps used in Examples 25-29 were all never-dried pulps ofapproximately 10% consistency shipped directly from the pulp mill inplastic-lined fiber drums. The procedure for preparing and treating thepulp with crosslinking chemicals included the steps of: (a) centrifugingthe never-dried pulp to a uniform consistency of approximately 34%; (b)treating the pulp with crosslinking chemicals in a large Hobart mixer ata consistency of approximately 5%; (c) centrifuging the treated pulp toa consistency of approximately 36% (higher now due to retained chemicalsolids); and (d) delumping the centrifuged, treated pulp in the Hobartmixer to achieve uniform particle size.

In all the examples, the jet drier system as described above was used tosingulate and dry the fibers. After passing through the jet drier, thedry singulated fibers were first collected and then cured in an oven.Crosslinking was only partially effected in the jet drier. Crosslinkingwas completed by curing the treated fiber for several minutes at anelevated temperature in a curing oven.

Testing of crosslinked fiber often includes sonic fractionation todetermine the percentage of knots, accepts, and fines as describedabove.

The primary attributes of crosslinked fiber are high bulk and retentionof bulk when wet. The FAQ test is used for measuring both wet and drybulks. “Resaturation bulk at 0.6 kPa” is usually the test result that isof most interest and is the value used when FAQ results are listed inthe examples. FAQs for commercially available crosslinked fibertypically range from 13.5 to 19.0 cc/g with higher values beingpreferred.

Example 25

In this example, bleached, never-dried Southern Pine was used. Thecrosslinker was DMDHEU. The post-jet drier cure time was about 5 minutesat 170° C. TABLE 25 Singulated Pulp Crosslinked With DMDHEU. ManifoldOutlet Crosslink Temp. Temp. Null Press. Knots Accepts Fines FAQ Run #(% ODF) (C.) (C.) (in of H₂O) (%) (%) (%) (cc/g) 91 2.0 220 135 −4.5 4.079.3 16.7 13.6 92 3.0 220 132 −4.5 4.3 79.0 16.7 13.6 93 4.0 220 135−4.5 4.1 78.9 17.0 13.6 94 2.0 200 115 −4.5 4.3 80.2 15.5 13.7 95 3.0200 112 −4.5 5.0 79.7 15.3 13.6 96 4.0 200 113 −4.5 4.8 77.6 17.6 13.8

Example 26

In this example, bleached, never-dried Southern Pine pulp was used. Thecrosslinker was citric acid. The post-drier cure time was about 5minutes at 170° C. TABLE 26 Singulated Pulp Crosslinked With Citric AcidManifold Outlet Null Crosslink Temp. Temp. Press. (in Knots AcceptsFines Run # (% ODF) (C.) (C.) of H₂O) (%) (%) (%) FAQ (cc/g) 97 5.7 200110 −4.5 4.1 79.9 16.0 15.1 98 5.7 200 112 −4.0 4.7 81.2 14.1 14.9 995.7 200 113 −4.0 3.7 82.6 13.7 15.1 100 11.5 200 113 −4.5 5.2 81.5 13.316.3 101 11.5 200 113 −4.5 3.9 83.6 12.5 16.2 102 11.5 200 116 −4.0 3.682.9 13.5 16.0

Example 27

In this example, bleached, never-dried Southern Pine was used. Thecrosslinker was Malic acid. The post-drier cure time was about 20minutes at 185° C. TABLE 27 Singulated Pulp Crosslinked With Malic AcidManifold Outlet Crosslink Temp. Temp. Null Press. Knots Accepts FinesFAQ Run # (% ODF) (C.) (C.) (in of H₂O) (%) (%) (%) (cc/g) 103 10.0 180106 −2.0 5.5 77.9 16.6 16.1 104 10.0 180 108 −4.5 3.7 79.4 16.9 16.3 10510.0 200 127 −2.0 4.2 80.9 14.9 16.1 106 10.0 200 123 −4.5 3.7 82.4 13.916.3 107 10.0 220 130 −1.5 4.0 80.9 15.1 16.3 108 10.0 220 135 −4.5 3.981.0 15.1 16.3 109 10.0 220 129 −6.0 3.9 82.9 13.2 16.4

Example 28

In this example, unbleached, never-dried Southern pine was noted. Thecrosslinker was Malic acid. The post-drier cure time was about 4 minutesat 200° C. TABLE 28 Singulated Pulp Crosslinked With Malic AcidCrosslink Manifold Outlet Null Press. Knots Accepts Fines FAQ Run # (%ODF) Temp. (C.) Temp. (C.) (in of H₂O) (%) (%) (%) (cc/g) 110 10.0 185106 −4.5 0.3 87.3 12.4 17.6 111 10.0 185 100 −6.5 0.5 88.4 11.1 18.0 11210.0 200 116 −4.5 0.7 87.8 11.5 17.9 113 10.0 200 110 −6.0 0.3 87.7 12.018.1 114 10.0 185 124 −5.5 0.7 86.2 13.1 17.8

Example 29

In this example, unbleached, never-dried Southern pine was used. Thecrosslinker was Malic acid. The post-drier cure time was 4 minutes at200° C. TABLE 29 Singulated Pulp Crosslinked With Malic Acid CrosslinkManifold Outlet Null Press. Knots Accepts Fines FAQ Run # (% ODF) Temp.(C.) Temp. (C.) (in of H₂O) (%) (%) (%) (cc/g) 115 2.0 200 118 −5.5 2.084.1 13.9 15.9 116 4.0 200 118 −5.5 2.2 84.4 13.4 17.1 117 6.0 200 119−5.0 2.0 83.0 15.0 17.3 118 8.0 200 118 −5.0 1.3 83.8 14.9 17.9

While the preferred embodiment of the invention has been illustrated anddescribed, it will be appreciated that various changes can be madetherein without departing from the spirit and scope of the invention.

1. A drying system for the processing of pulp into singulated and driedfibers comprising: a jet drier with a jet conduit, said jet conduitconfigured to freely circulate said pulp in a loop without additionalmechanical intervention, a pulp intake for delivery of pulp into the jetconduit, a manifold for air intake into the jet conduit, said manifoldincluding nozzles for inducing flow in said conduit and causing feed airto impinge on pulp circulating in said conduit, and a fiber outlet forremoval of singulated and dried fibers, outlet air and fines from thejet conduit; a pulp supply station coupled to the pulp intake forsupplying a feed pulp to the pulp intake, the pulp supply stationincluding a treatment supply source for delivering a crosslinker to thepulp; an air supply station coupled to the manifold for delivering airto the manifold; an outlet flow conduit coupled to the fiber outlet forthe removal of the fibers, outlet air, and fines from the jet conduit;and a fiber separation station coupled to the outlet flow conduit forseparating the fibers from the outlet air.
 2. The drying system of claim1, wherein the pulp supply station further includes a first dewateringdevice and a second dewatering device in flow communication with thefirst dewatering device; the first dewatering device receiving a pulpsupply having a liquid content, removing a portion of the liquidcontent, and sending a dewatered supply pulp to the second dewateringdevice; the treatment supply source delivering the crosslinker to thedewatered supply pulp prior to entry into the second dewatering device;and the second dewatering device removing additional liquid content fromthe treated and dewatered supply pulp and sending a treated feed pulp tothe jet drier pulp intake.
 3. The drying system of claim 1, wherein thepulp supply station further includes a pulp feed device coupled to thepulp intake for delivering the feed pulp to the pulp intake whileminimizing the amount of air flow through the pulp supply station, thepulp feed device being a rotary airlock including a rotor housing and arotor rotatably mounted within the rotor housing, the rotor having rotorvanes for transporting the feed pulp, wherein the rotor vanes and rotorhousing are sized so that a gap exists between the rotor vanes and therotor housing to prevent the feed pulp from jamming the rotary airlock.